The Qt Test testing framework [0] supports output in TAP format, when the test binary is passed the -tap command-line option [1]. (I would welcome any bug reports against the output it produces, if it turns out to be out of date or otherwise imperfect.) A mention on your list of producers would be welcome ;^>
[0] https://doc.qt.io/qt-6/qttest-index.html
[1] https://doc.qt.io/qt-6/qtest-overview.html#logging-options