In some circumstances it may be useful to specify the Qt version qtpy should use without without specifying which implementation to use. Currently it is only possible leave it up to qtpy to decide or to exactly specify the API using the QT_API environment variable.

In my particular use case I would need this feature in an application using QtPdf (which is only available in Qt6) but am indifferent whether PyQt6 or PySide6 should be used. I am aware that it is possible to set QT_API=pyqt6 and pyqt will fall back to PySide6 when PyQt6 is not available but I would consider this a bit unsatisfactory since it will trigger a warning for an unproblematic case, the actual intention does not become clear when looking at the code and it does not work when only Qt5 should be used instead.

This feature could be realized by allowing to set QT_API to a Qt version , e.g. QT_API=Qt6 or by allowing to set QT_API to a list of values, e.g. QT_API=pyqt6,pyside6.