All games I want to play run very well and mostly the process is just "install -> play".

This is largely true for games running directly through Steam, it can get pretty annoying for games that exist outside Steam.

Especially when you have to do things like apply an ".msi" style patch to a game .

It's doable, but the number of steps and tools you may have to pull in (such as protontricks) does get to be a bit of a pain at times.

The trick I have is that I add the game and all related windows exes to steam in the same file system. When you run a game on proton through steam, it makes this virtual file system thats matches a game appid, or a uuid. So youll get a folder somewhere thats like 12345566778. You can add that file to an override for a different application, and have it run on that application file system. So if you add a patcher, mod tool etc, you can use it just like its in windows.

For example: Add Diablo 2 exe to Steam. Run Diablo 2 in proton. This creates a folder like 123455 /home/user/.local/share/Steam/steamapps/compatdata/123455/. Then Add LOD to Steam, add this to the system launch STEAM_COMPAT_DATA_PATH=/home/user/.local/share/Steam/steamapps/compatdata/123455/ and you can run the installer on the older file data. Do the same for a mod patcher, etc.

Agreed, but people should definitely try Lutris. It's nearly as painless as Steam now for GOG and many other stores.

Lutris recipes often work out of the box as well. It's as simple as hitting "install" on the Lutris app.