There is built-in support for some reshade functionality in SteamOS's gamescope. But by how adamant you are, I'm sure you already knew about it, and it's shortcomings.
For others, the built in support is enough if you'd like to apply some retro shading "filters" to a game or two you play. I really enjoy this VHS effect for games like The Messenger and Slipstream https://github.com/safijari/Reshadeck/blob/main/defaults/sha...
https://github.com/safijari/Reshadeck
For others, the built in support is enough if you'd like to apply some retro shading "filters" to a game or two you play. I really enjoy this VHS effect for games like The Messenger and Slipstream https://github.com/safijari/Reshadeck/blob/main/defaults/sha...