I can well understand your displeasure. My first contact with Linux was with my Blackbird. At the beginning it was really hard to understand everything. But with time it gets better.
I didn't update to firmware 2.0 because it has too many disadvantages for me.
But IIRC, you have to decompress the image-bmc twice.
Also a good howto has been written by ClassicHasClass:
https://www.talospace.com/2020/02/messing-with-new-20-bmc.htmlI'm pretty sure the GPU issues has nothing to do with the BMC firmware.
Could or have you already posted your xorg config file?
And how is your computer connected to the display?
Do you use the AST GPU till Petitboot and then you switch to the AMD GPU or do you only use the AMD GPU?