Proton is usable even without Steam, you simply publish the Windows version only and people will figure it out. If you make sure it works with the Steam Compatibility layer (Proton), it’s easy to run anywhere on Linux.
For GOG the easiest would be Heroic Games Launcher which also uses Proton.
I personally am fine with Proton, the native Linux build usually doesn’t work as well as the Windows one because devs don’t usually care because of smaller market share (or don’t have the time as is often the case with indie studios).
What’s the name of the game? I’ll add it to my wishlist if it sounds like something I’d enjoy.
Also, if I may ask, do a GOG release, I do 90% of my gaming there.
Always use a VPN. With torrents you actively share the file which is illegal pretty much anywhere.
Even if no one cares today, someone might tomorrow.
Good luck! I did the same recently. I wrote my own blog system, though. I can share it with you, but I’m not sure it’s the best for anyone else, there were some shortcuts taken given I did not intend to share it.
You can check out my blog and let me know whether you want to try it: https://chrastecky.dev/ (or federated: !programming@chrastecky.dev, !3d-printing@chrastecky.dev, !gaming@chrastecky.dev).