I would like to offer some assistance but I know my knowledge scuba tanks will not permit me to go to the depth you are working at.
I only see blank stares and blacking out from the bends of working at such depth.
Good luck. I will enjoy tracking your progress from the surface.
So, I have been working with the Raspberry PI 4 recently and I have come across some issue relating to the use case for the end user.
fbset part of the firmware does not seem to work as well :-
1. Only depth 32bit works.
2. Changing the frame buffer size does not always change the full frame buffer. Instead it will not change the virtual frame buffer . e.g change from 640x480 to 320x240 you only see a quarter of the screen.
tvsercice only works with composite and hdmi. You are no longer able to change resolutions of the DPI output. it is possible if a EDID for you screen is available otherwise you'll need to create a fake EDID.
vc4-fkms-v3d is enabled by default which means fbset and tvservice do not work without disabling it. With it enabled your meant to have full xrandr x11 environment. However, changing to some(many) resolutions does not work and you will get a crtc 0 error, using the same methods to change resolutions under X with older models (Pi3) works flawlessly.
I have had discussion on the Raspberry PI git, only answers I seem to get is that this is normal behaviour.
Please let me know if anyone here has come across other issues or even found ways around the above.