Moved to: https://gitlab.com/ExistingPerson08/gamescope-session-pp
Gamescope session ++ allows you to launch Steam Gamescope session inside your desktop enviroment. It also allows yout to easilly switch between Steam big picture and Steam desktop modes.
To make this to work, you'll need Steam and gamescope installed. Then just copy files from this repo into your root folder and restart desktop.
Polkit rules in /etc are only needed to make this work on accounts that are not in wheel group.