[imtringued]

There is also pretty good Linux support. So if you wanted to tick the Linux box you only have to make sure your game works under proton which generally just means avoiding proprietary anti cheat and Microsoft specific codecs/fonts.

I know a franchise whose games ran with 99% compatibility in proton except the cutscenes which used a proprietary codec. Proton then got a patch and just shows a static image during cut scenes while the rest of the game works perfectly. The developer can fix it by reencoding the cutscenes. No need for explicit Linux support.