No need get window. You need somes tools though.
From the stock app market (called discover) :
- Transmission
- Lutris
- ProtonUp-QT to install ProtonGE
From GitHub:
- Decky (and the addon SteamGridDB)
On desktop mode.
I download my games as torrent from dodirepack or fitgirl with the software transmission(from stock appshop).
Once I have a game I use Lutris(from stock appshop) to execute the installer. Install games on :Z Wich is the steals file system.
Then I add the game to steam on desktop mode.
I set the compatibility in the game options mode on proton or protonGE.
And I rename the game to their steamid to be able to search for contrôler config. (Find steam game I'd on the site SteamDB)
In game mode
I then setup images for the games with the addon SteamGridDB installed from Decky (and addon loader for steamdeck)
If I have trouble running game I use protonGE which I installed with ProtonUp-QT (from stock appshop)
Mostly installing games from outside the steam shop.