it's really not... hell, i was running BSD on a Mac Quadra back in 1999... what's hard is hardware, but i've seen nvidia proprietary drivers running on a BSD installation back in 2019... yes, it had X on it too

really it's just a matter of - how to monetize providing this... mobile hardware is a big problem but PC hardware with UEFI and AMD64/ARM64 is doable, and hardware you can fully (so to speak) replace the OS on like Pixels can do this too, the differences to the other major platform now are steadily reducing