Lol I’m stealing this

Yeah both heroic game launcher and lutris will install gog games, heroic is a bit easier though. Then from desktop mode you just right click on the game shortcut and hit “add to steam” so it’ll show up in your steam library (in the non steam games section).

You can also add heroic or lutris to the non steam games section, so that you can use it as a separate game launcher/library manager if you want.