- GFX cards would be the same ones already supported in PCIe(and some AGP ones) Macs and X5000/SAM460, so no real problem. Actually it would be slightly better as there would be no issue of needing a 2nd card to access FirmWare/BIOS/BootMenu.
- I don't think it would need to be super specific to a certain board. AFAIR Bigfoot used a MSI B450 board and I'm almost certain that the variations to other B450 would be less than between different revisions of some Macs all sharing the same model number.
- B450 boards with AM4 CPU can still be bought new and GFX cards are easy enough to find
Even if you would need be limited to a few specific boards and a Ryzen3600 (which Bigfoot used) that is still easier to find than a working PCIe G5 which have become slim pickings over the past few years.
So no, HW is not the issue, what would be an issue (IMO) is that the underusage of the HW would be even more apparent when everyone has AT LEAST 4 cores and 8GB of RAM.
