Need for Speed: Unbound has an unsupported status on Steam Deck, but after setting Proton Experimental, the game works fine! I haven’t had a chance to play longer yet, but at first glance the whole production is very playable on Steam Deck.
Surprise! Need for Speed Unbound is playable on Steam Deck with Proton Experimental!
NFS: Unbound has a lot of graphics options, including support for AMD FSR 2.1 scaling, but even on the lowest settings it has minor performance issues. Valve has not yet prepared a shader cache for this game, so for the first minutes of gameplay the stuttering is annoying, but after a while you can see an improvement in fluidity.
I think the 40FPS limit is achievable for Need for Speed: Unbound, but I have yet to test it closely. I will publish optimized settings for this game soon.