You can also enable Gamescope via Steam. In the properties for each game you can pass a command line the same way you would for enabling FSR in Desktop Steam.
This is for Gamemode:
gamemoderun gamescope –mangoapp -w 640 -h 380 -W 1920 -H 1080 -F fsr -f – %command%
Use this if you want Mangohud and Gamemode:
env MANGOHUD_CONFIG=”fsr,fps_value.gamemode” gamemoderun gamescope –mangoapp -w 640 -h 380 -W 1920 -H 1080 -F fsr -f – %command%
This is if you only want to enable FSR via desktop steam
WINE_FULLSCREEN_FSR=1 WINE_FULLSCREEN_FSR_MODE=ultra %command%