Is it the ghostbsd/xconfig repo's shell file at xconfig /bin/xconfig ? In the function start_drm_modesetting() ? Or is it possibly the surrounding start_xorg() when it reaches the fail_safe() function? I am curious how much is the minimum to transfer to a plain FreeBSD install to use to get X going ...

But how does it figure out the settings that work?
If you can even point me to the code I am happy to read through.

How is the 20.04 installer doing this magic? I have never successfully gotten xorg to work with my Radeon RX 570 on FreeBSD nor previously with TrueOS or GhostBSD or OpenBSD or NetBSD. I had to use scfb or (more usefully) switch the monitor cable to the Intel integrated graphics HDMI port. Now I wen...