I played the play tests on my steamdeck, and it does seem to run without any errors or issues, but the performance is not good on the Steam Deck’s APU (probably because they make a lot of use of dynamic ray-traced lighting effects similar to The Finals).

I believe Embark Studios stated for the Finals that they run each update of their game through Codeweavers to maintain compatibility for Proton users, and I’d imagine that’s not going to change anytime soon. I think it’s kernel level anticheat for windows, Proton EAC for linux.