I know this has been mentioned before, but it’s worth mentioning again as 3.5 is released in Stable channel. There is a Nested Desktop app you can add to steam from Desktop mode. This will allow you to manage desktop files and use apps from within gaming mode, without having to leave gaming mode. Desktop works just like another game (app) in Steam.
In the Application Launcher, search for “Nested Desktop” and add to Steam. There are community controller profiles, that you can use so that you can use trackpad and navigate easily.
I love that this is an official feature, but it’s straight up not working for me. It switches to the Steam Deck logo with the little loading circle at the bottom and it stays frozen like that forever, no matter how long I wait.