Kinda agree. New graphics card is deffo a nuclear option. I’m running pop os and haven’t come across a game I can’t run as it’s got the Nvidia drivers built it. I’d probably try swap distro before buying a new card just in case it’s that. That’s just time and effort rather than buying something that ‘might’ work.
Probably also worth noting that valve are updating the proton drivers all the time, they want the entire steam catalogue to work on steam deck so I would expect every game to work on proton over time. Might just be a waiting game tbh.
Not sure if different or just tuned to work better with the distro or something else entirely.