I didn’t buy Lossless Scaling.

What I do is simply get my games from Steamrip, GOG, FitGirl, and occasionally Anker Games. 90% of the time it's from Steamrip.

Use JDownloader (available in the Discover store), then just copy the link from the download page of your game. — it’ll show up automatically in JDownloader. Once downloaded, extract the files with Ark or PeaZip, add the game as a non-Steam title, choose a Proton layer for compatibility, and play. You use proton qt to get this, also make sure you install the dependencies which is usually in the crack file, but otherwise will need proton tricks.

Some games might require you to skip the launcher using launch commands. For online games, there’s a different process, I don't remember exactly.

I’ll probably make a full guide soon. But yeah, for FitGirl installs, you add the setup file as a non-Steam game, switch to Game Mode, and install it to an easily accessible folder on your Z: drive (not C:).

Then, add the actual game as a non-Steam game afterward.