At that point you might as well not have a kernel level anti cheat and companies who insist on kernel level anti cheat will block wine. The only solutions I see are

1. Developers mainly use server side anti cheat
2. They make native Linux games
3. Distros provide a way to ensure a untainted (signed) kernel

Obsidian is proprietary though

Just FYI while it uses X11 in desktop mode, in game mode it uses Wayland. It’s probably still on 5.X because for the main use case of the deck plasma 6 isn’t really that much of an upgrade and they probably prefer having a stable system than having some new stuff most users won’t actually use

It’s pretty much impossible to get gnome on regular steamOS. Bazzite also has some additional stuff compared to steamOS, namely printing support, optional full disk encryption, newer plasma version (SteamOS should be on 5.27 or what ever the latest version of plasma 5 is). Nothing major, but small stuff. Bazzite has the disadvantage of not being installed by default and less of a backing (Valve still is a big company). Most things on steam deck are easily replaceable, except for the battery, but not necessarily upgradable. If you want to upgrade storage be aware that the steam deck uses a relatively rare nvme size, so prizes might be higher than expected (other than that it’s quite simple). The screen also can be upgraded but that requires a sizable amount of work, same with ram.