Windows also does not have 100% compatibility. Try playing something like age of wonders 1 on current windows. I could run in out of the box on steam deck but not on my pc that at the time had windows 10. I think Windows no longer has compatibility with win 98 and lower but i might be misremembering.

Eh they’ll find something else to whine about

The lazy companies developing anti-cheats will likely not allow that. Some games even refuse VMs, it’s incredibly stupid.

XBOX must have 100% of games available on Playstation. Otherwise nobody will ever switch.