While you _can_ use their launcher, you don't _have_ to. Once you buy the game, you can just download the installer and run it to install on your box. If you want you can save the install package somewhere if you think you'll enjoy the game for years to come and don't want to be dependent on GOG.

I also found out that they have quite a few fairly recent games. Maybe not the top-10 big budget (however they partner with RedProject so they do have Cyberpunk) but they have plenty of solid indy games from 2015 - 2020, and some more recent.