diff --git a/python/gui/auto_generated/qgisinterface.sip.in b/python/gui/auto_generated/qgisinterface.sip.in
index fa03eb23571f..c56c47b0c061 100644
--- a/python/gui/auto_generated/qgisinterface.sip.in
+++ b/python/gui/auto_generated/qgisinterface.sip.in
@@ -986,6 +986,14 @@ Opens the options dialog. The ``currentPage`` argument can be used to force
 the dialog to open at a specific page.
 
 .. versionadded:: 3.0
+%End
+
+    virtual void showProjectPropertiesDialog( const QString &currentPage = QString() ) = 0;
+%Docstring
+Opens the project properties dialog. The ``currentPage`` argument can be used to force
+the dialog to open at a specific page.
+
+.. versionadded:: 3.16
 %End
 
     virtual void buildStyleSheet( const QMap<QString, QVariant> &opts ) = 0;
@@ -1176,6 +1184,33 @@ Unregister a previously registered tab in the options dialog.
 .. seealso:: :py:func:`registerOptionsWidgetFactory`
 
 .. versionadded:: 3.0
+%End
+
+    virtual void registerProjectPropertiesWidgetFactory( QgsOptionsWidgetFactory *factory ) = 0;
+%Docstring
+Register a new tab in the project properties dialog.
+
+.. note::
+
+   Ownership of the factory is not transferred, and the factory must
+   be unregistered when plugin is unloaded.
+
+.. seealso:: :py:class:`QgsOptionsWidgetFactory`
+
+.. seealso:: :py:func:`unregisterProjectPropertiesWidgetFactory`
+
+.. versionadded:: 3.16
+%End
+
+    virtual void unregisterProjectPropertiesWidgetFactory( QgsOptionsWidgetFactory *factory ) = 0;
+%Docstring
+Unregister a previously registered tab in the options dialog.
+
+.. seealso:: :py:class:`QgsOptionsWidgetFactory`
+
+.. seealso:: :py:func:`registerProjectPropertiesWidgetFactory`
+
+.. versionadded:: 3.16
 %End
 
     virtual void registerDevToolWidgetFactory( QgsDevToolWidgetFactory *factory ) = 0;
diff --git a/src/app/qgisapp.cpp b/src/app/qgisapp.cpp
index 590f2153670f..cd2d42982334 100644
--- a/src/app/qgisapp.cpp
+++ b/src/app/qgisapp.cpp
@@ -12179,6 +12179,17 @@ QMap< QString, QString > QgisApp::projectPropertiesPagesMap()
     sProjectPropertiesPagesMap.insert( QCoreApplication::translate( "QgsProjectPropertiesBase", "Temporal" ), QStringLiteral( "mTemporalOptions" ) );
   } );
 
+  int idx = sProjectPropertiesPagesMap.count();
+  for ( const QPointer< QgsOptionsWidgetFactory > &f : qgis::as_const( mProjectPropertiesWidgetFactories ) )
+  {
+    // remove any deleted factories
+    if ( f )
+    {
+      sProjectPropertiesPagesMap.insert( f->title(), f->title() );
+    }
+    idx++;
+  }
+
   return sProjectPropertiesPagesMap;
 }
 
@@ -12620,6 +12631,16 @@ void QgisApp::unregisterOptionsWidgetFactory( QgsOptionsWidgetFactory *factory )
   mOptionsWidgetFactories.removeAll( factory );
 }
 
+void QgisApp::registerProjectPropertiesWidgetFactory( QgsOptionsWidgetFactory *factory )
+{
+  mProjectPropertiesWidgetFactories << factory;
+}
+
+void QgisApp::unregisterProjectPropertiesWidgetFactory( QgsOptionsWidgetFactory *factory )
+{
+  mProjectPropertiesWidgetFactories.removeAll( factory );
+}
+
 void QgisApp::registerDevToolFactory( QgsDevToolWidgetFactory *factory )
 {
   mDevToolFactories << factory;
@@ -14115,7 +14136,16 @@ void QgisApp::projectProperties( const QString &currentPage )
   // dialog results in the construction of the spatial reference
   // system QMap
   QApplication::setOverrideCursor( Qt::WaitCursor );
-  QgsProjectProperties *pp = new QgsProjectProperties( mMapCanvas, this );
+
+  QList< QgsOptionsWidgetFactory * > factories;
+  const auto constProjectPropertiesWidgetFactories = mProjectPropertiesWidgetFactories;
+  for ( const QPointer< QgsOptionsWidgetFactory > &f : constProjectPropertiesWidgetFactories )
+  {
+    if ( f )
+      factories << f;
+  }
+  QgsProjectProperties *pp = new QgsProjectProperties( mMapCanvas, this, QgsGuiUtils::ModalDialogFlags, factories );
+
   // if called from the status bar, show the projection tab
   if ( mShowProjectionTab )
   {
diff --git a/src/app/qgisapp.h b/src/app/qgisapp.h
index 62d5d33f49ea..45039581443a 100644
--- a/src/app/qgisapp.h
+++ b/src/app/qgisapp.h
@@ -733,6 +733,12 @@ class APP_EXPORT QgisApp : public QMainWindow, private Ui::MainWindow
     //! Unregister a previously registered tab in the options dialog
     void unregisterOptionsWidgetFactory( QgsOptionsWidgetFactory *factory );
 
+    //! Register a new tab in the project properties dialog
+    void registerProjectPropertiesWidgetFactory( QgsOptionsWidgetFactory *factory );
+
+    //! Unregister a previously registered tab in the project properties dialog
+    void unregisterProjectPropertiesWidgetFactory( QgsOptionsWidgetFactory *factory );
+
     //! Register a dev tool factory
     void registerDevToolFactory( QgsDevToolWidgetFactory *factory );
 
@@ -2555,6 +2561,7 @@ class APP_EXPORT QgisApp : public QMainWindow, private Ui::MainWindow
 
     QList<QgsMapLayerConfigWidgetFactory *> mMapLayerPanelFactories;
     QList<QPointer<QgsOptionsWidgetFactory>> mOptionsWidgetFactories;
+    QList<QPointer<QgsOptionsWidgetFactory>> mProjectPropertiesWidgetFactories;
 
     QList<QgsDevToolWidgetFactory * > mDevToolFactories;
 
diff --git a/src/app/qgisappinterface.cpp b/src/app/qgisappinterface.cpp
index dde798f9fa48..823e576c03d3 100644
--- a/src/app/qgisappinterface.cpp
+++ b/src/app/qgisappinterface.cpp
@@ -445,6 +445,11 @@ void QgisAppInterface::showOptionsDialog( QWidget *parent, const QString &curren
   return qgis->showOptionsDialog( parent, currentPage );
 }
 
+void QgisAppInterface::showProjectPropertiesDialog( const QString &currentPage )
+{
+  return qgis->showProjectProperties( currentPage );
+}
+
 QMap<QString, QVariant> QgisAppInterface::defaultStyleSheetOptions()
 {
   return qgis->styleSheetBuilder()->defaultOptions();
@@ -546,6 +551,16 @@ void QgisAppInterface::unregisterOptionsWidgetFactory( QgsOptionsWidgetFactory *
   qgis->unregisterOptionsWidgetFactory( factory );
 }
 
+void QgisAppInterface::registerProjectPropertiesWidgetFactory( QgsOptionsWidgetFactory *factory )
+{
+  qgis->registerProjectPropertiesWidgetFactory( factory );
+}
+
+void QgisAppInterface::unregisterProjectPropertiesWidgetFactory( QgsOptionsWidgetFactory *factory )
+{
+  qgis->unregisterProjectPropertiesWidgetFactory( factory );
+}
+
 void QgisAppInterface::registerDevToolWidgetFactory( QgsDevToolWidgetFactory *factory )
 {
   qgis->registerDevToolFactory( factory );
diff --git a/src/app/qgisappinterface.h b/src/app/qgisappinterface.h
index e98f5abab68c..23d3348c886b 100644
--- a/src/app/qgisappinterface.h
+++ b/src/app/qgisappinterface.h
@@ -115,6 +115,7 @@ class APP_EXPORT QgisAppInterface : public QgisInterface
     QList<QgsLayoutDesignerInterface *> openLayoutDesigners() override;
     QgsLayoutDesignerInterface *openLayoutDesigner( QgsMasterLayoutInterface *layout ) override;
     void showOptionsDialog( QWidget *parent = nullptr, const QString &currentPage = QString() ) override;
+    void showProjectPropertiesDialog( const QString &currentPage = QString() ) override;
     QMap<QString, QVariant> defaultStyleSheetOptions() override;
     void buildStyleSheet( const QMap<QString, QVariant> &opts ) override;
     void saveStyleSheetOptions( const QMap<QString, QVariant> &opts ) override;
@@ -145,6 +146,8 @@ class APP_EXPORT QgisAppInterface : public QgisInterface
     void unregisterMapLayerConfigWidgetFactory( QgsMapLayerConfigWidgetFactory *factory ) override;
     void registerOptionsWidgetFactory( QgsOptionsWidgetFactory *factory ) override;
     void unregisterOptionsWidgetFactory( QgsOptionsWidgetFactory *factory ) override;
+    void registerProjectPropertiesWidgetFactory( QgsOptionsWidgetFactory *factory ) override;
+    void unregisterProjectPropertiesWidgetFactory( QgsOptionsWidgetFactory *factory ) override;
     void registerDevToolWidgetFactory( QgsDevToolWidgetFactory *factory ) override;
     void unregisterDevToolWidgetFactory( QgsDevToolWidgetFactory *factory ) override;
     void registerCustomDropHandler( QgsCustomDropHandler *handler ) override;
diff --git a/src/app/qgsprojectproperties.cpp b/src/app/qgsprojectproperties.cpp
index 7c6fb14ec4d9..9b41f4e10c41 100644
--- a/src/app/qgsprojectproperties.cpp
+++ b/src/app/qgsprojectproperties.cpp
@@ -76,7 +76,7 @@
 //qt includes
 #include <QInputDialog>
 #include <QFileDialog>
-#include <QHeaderView>  // Qt 4.4
+#include <QHeaderView>
 #include <QMessageBox>
 #include <QDesktopServices>
 #include <QAbstractListModel>
@@ -87,7 +87,7 @@ const char *QgsProjectProperties::GEO_NONE_DESC = QT_TRANSLATE_NOOP( "QgsOptions
 
 //stdc++ includes
 
-QgsProjectProperties::QgsProjectProperties( QgsMapCanvas *mapCanvas, QWidget *parent, Qt::WindowFlags fl )
+QgsProjectProperties::QgsProjectProperties( QgsMapCanvas *mapCanvas, QWidget *parent, Qt::WindowFlags fl, const QList<QgsOptionsWidgetFactory *> &optionsFactories )
   : QgsOptionsDialogBase( QStringLiteral( "ProjectProperties" ), parent, fl )
   , mMapCanvas( mapCanvas )
   , mEllipsoidIndex( 0 )
@@ -971,6 +971,24 @@ QgsProjectProperties::QgsProjectProperties( QgsMapCanvas *mapCanvas, QWidget *pa
 
   mBearingFormat.reset( QgsProject::instance()->displaySettings()->bearingFormat()->clone() );
 
+  const auto constOptionsFactories = optionsFactories;
+  for ( QgsOptionsWidgetFactory *factory : constOptionsFactories )
+  {
+    QListWidgetItem *item = new QListWidgetItem();
+    item->setIcon( factory->icon() );
+    item->setText( factory->title() );
+    item->setToolTip( factory->title() );
+
+    mOptionsListWidget->addItem( item );
+
+    QgsOptionsPageWidget *page = factory->createWidget( this );
+    if ( !page )
+      continue;
+
+    mAdditionalProjectPropertiesWidgets << page;
+    mOptionsStackedWidget->addWidget( page );
+  }
+
   restoreOptionsBaseUi();
 
 #ifdef QGISDEBUG
@@ -1525,6 +1543,11 @@ void QgsProjectProperties::apply()
 
   QgsProject::instance()->displaySettings()->setBearingFormat( mBearingFormat->clone() );
 
+  for ( QgsOptionsPageWidget *widget : qgis::as_const( mAdditionalProjectPropertiesWidgets ) )
+  {
+    widget->apply();
+  }
+
   //refresh canvases to reflect new properties, eg background color and scale bar after changing display units.
   for ( QgsMapCanvas *canvas : constMapCanvases )
   {
@@ -2524,6 +2547,17 @@ void QgsProjectProperties::showHelp()
   {
     link = QStringLiteral( "working_with_ogc/server/getting_started.html#prepare-a-project-to-serve" );
   }
+
+  // give first priority to created pages which have specified a help key
+  for ( const QgsOptionsPageWidget *widget : qgis::as_const( mAdditionalProjectPropertiesWidgets ) )
+  {
+    if ( widget == activeTab )
+    {
+      link = widget->helpKey();
+      break;
+    }
+  }
+
   QgsHelp::openHelp( link );
 }
 
diff --git a/src/app/qgsprojectproperties.h b/src/app/qgsprojectproperties.h
index ceb22835b97c..625f0e959cb3 100644
--- a/src/app/qgsprojectproperties.h
+++ b/src/app/qgsprojectproperties.h
@@ -17,8 +17,10 @@
  ***************************************************************************/
 
 
-#include "qgsoptionsdialogbase.h"
 #include "ui_qgsprojectpropertiesbase.h"
+
+#include "qgsoptionsdialogbase.h"
+#include "qgsoptionswidgetfactory.h"
 #include "qgis.h"
 #include "qgsunittypes.h"
 #include "qgsguiutils.h"
@@ -26,6 +28,8 @@
 #include "qgshelp.h"
 #include "qgis_app.h"
 
+#include <QList>
+
 class QgsMapCanvas;
 class QgsRelationManagerDialog;
 class QgsStyle;
@@ -35,6 +39,7 @@ class QgsMetadataWidget;
 class QgsTreeWidgetItem;
 class QgsLayerCapabilitiesModel;
 class QgsBearingNumericFormat;
+class QgsOptionsPageWidget;
 
 /**
  * Dialog to set project level properties
@@ -48,7 +53,8 @@ class APP_EXPORT QgsProjectProperties : public QgsOptionsDialogBase, private Ui:
 
   public:
     //! Constructor
-    QgsProjectProperties( QgsMapCanvas *mapCanvas, QWidget *parent = nullptr, Qt::WindowFlags fl = QgsGuiUtils::ModalDialogFlags );
+    QgsProjectProperties( QgsMapCanvas *mapCanvas, QWidget *parent = nullptr, Qt::WindowFlags fl = QgsGuiUtils::ModalDialogFlags,
+                          const QList<QgsOptionsWidgetFactory *> &optionsFactories = QList<QgsOptionsWidgetFactory *>() );
 
     ~QgsProjectProperties() override;
 
@@ -250,6 +256,8 @@ class APP_EXPORT QgsProjectProperties : public QgsOptionsDialogBase, private Ui:
     int mEllipsoidIndex;
     bool mBlockCrsUpdates = false;
 
+    QList< QgsOptionsPageWidget * > mAdditionalProjectPropertiesWidgets;
+
     std::unique_ptr< QgsBearingNumericFormat > mBearingFormat;
 
     //! populate WMTS tree
diff --git a/src/gui/qgisinterface.h b/src/gui/qgisinterface.h
index 32b4840a458c..f151d5554fcf 100644
--- a/src/gui/qgisinterface.h
+++ b/src/gui/qgisinterface.h
@@ -848,6 +848,13 @@ class GUI_EXPORT QgisInterface : public QObject
      */
     virtual void showOptionsDialog( QWidget *parent = nullptr, const QString &currentPage = QString() ) = 0;
 
+    /**
+     * Opens the project properties dialog. The \a currentPage argument can be used to force
+     * the dialog to open at a specific page.
+     * \since QGIS 3.16
+     */
+    virtual void showProjectPropertiesDialog( const QString &currentPage = QString() ) = 0;
+
     /**
      * Generate stylesheet
      * \param opts generated default option values, or a changed copy of them
@@ -984,6 +991,24 @@ class GUI_EXPORT QgisInterface : public QObject
     */
     virtual void unregisterOptionsWidgetFactory( QgsOptionsWidgetFactory *factory ) = 0;
 
+    /**
+     * Register a new tab in the project properties dialog.
+     * \note Ownership of the factory is not transferred, and the factory must
+     *       be unregistered when plugin is unloaded.
+     * \see QgsOptionsWidgetFactory
+     * \see unregisterProjectPropertiesWidgetFactory()
+     * \since QGIS 3.16
+     */
+    virtual void registerProjectPropertiesWidgetFactory( QgsOptionsWidgetFactory *factory ) = 0;
+
+    /**
+     * Unregister a previously registered tab in the options dialog.
+     * \see QgsOptionsWidgetFactory
+     * \see registerProjectPropertiesWidgetFactory()
+     * \since QGIS 3.16
+    */
+    virtual void unregisterProjectPropertiesWidgetFactory( QgsOptionsWidgetFactory *factory ) = 0;
+
     /**
      * Register a new tool in the development/debugging tools dock.
      * \note Ownership of the factory is not transferred, and the factory must