Building QT with EGLFS support

Hello,
I’m trying to use the Radxa-Cm3 to deploy a custom Software, which needs to hardware decode/encode video and also run in EGLFS.
For this I can’t just use standart Qt, because it either doesn’t run in eglfs (qt5-base) or doesn’t have all the plugins I need (qtbase5-private-gles-dev).
I also need 5.15 so it looks like I need to build it myself.
I couldn’t find mkspecs for rk3566, so mine looks like : https://github.com/OpenHD/qt-device-configuration/blob/master/linux-RK3566-g%2B%2B/qmake.conf

I would really appreciate any help you could offer

thanks