I haven't tried a direct installation, but there's guides on how to install windows version of the itch app on steam deck. And through the app you can run the games. I used this method to play Villain SIM on SD after it was removed from Steam.
Thanks for the tip!
Just want to confrim for future handheld users, itch.io app on windows for ROG ALLY works to be able to use contoller settings.
