Firstly if you’re looking to upgrade your system and switch to Linux, I would recommend switching to team Red. For a variety of reasons really but generally they are a better value and also will just work better with Linux.

GOG games can be run on SteamOS and SteamOS-like distros through Heroic and Lutris. Though YMMV. You’re going to have a much better time playing games on Steam.

Valve is not going to give you support for GOG but Linux is a community-driven project and probably the vast majority of Linux users are going to want to run games from other stores.