Well, Steam at least uses Proton, so most of the games will be from Windows.
The only thing that Proton can't do is run recent Anti-cheat software like EAC.
Other than that, it's most likely that your favorite game will work fine, specially if it uses OGL/Vulkan.
AAIK, you also have the option to install W10/11.
Yes if I get this I'll be looking to install w10w11. I'm going to wait a bit though and see what people are saying about it. Although with the preorder issues sounds like I'll be forced to wait no matter what.