One nice thing about GoG Galaxy, at least a version I used a very long time ago, is it is actually an agnostic launcher as well. It could connect to Steam, and other services, to automatically manage your unified library. I have no idea if it's still like that on Windows or if the Linux version will be like that. It was very non-judgemental and not pushing purchases, like Steam does. This was like a decade ago though, so that may not be true anymore.