Running the attached QML should output to two screens (if connected):

qml screens.qml -platform eglfs

Prior to 6.5 qmlscene has to be used instead of qml (QTBUG-110112). This aborts with "EGLFS: OpenGL windows cannot be mixed with others."

Tested on Intel HW (OpenGL VENDOR: Intel RENDERER: Mesa Intel(R) UHD Graphics (CML GT2) VERSION: OpenGL ES 3.2 Mesa 22.2.5, Ubuntu 22.04 from VT) and on Raspberry Pi 4 (64bit, boot2qt). It works with Qt5.15 on both, though.

Besides, directing a single Window to a specific screen doesn't work in Qt6.5 (it will always be shown on the first). This is also working in Qt5.15.