Installation step is difficult to execute when in gaming mode whilst the Steam Deck is docked
Using an external controller when launching the game from Gamescope whilst the Steam Deck is docked is difficult because the file picker doesn't support the control with Steam Input Disabled (however this is the preferred way to play the game later on). The touch screen is still usable on the deck however pressing the Open button was impossible on the files. I had to get around this by setting a mouse only keybind to the deck itself and navigate the menu that way whilst keeping the deck docked.
IMO, it's a problem with Steam itself as far as i am concerned, all of my applications that uses file picker during gaming mode are very difficult to handle (e.g.: Proton/Wine-based Emulators, Chrome, Bottles, VLC, etc.), so i always resort to desktop mode, and get things done before going back.