Need something to keep your game saves backed up with a friendly UI? Ludusavi is one such project that's free and open source, so anyone can help with it. Cross-platform too across Linux, macOS and Windows!
The way it works is pretty interesting, with saved game data scraped from PCGamingWiki and then stored into a main file that's continually updated and downloaded when you use the app itself. It doesn't entirely rely on that though, as you can also add custom locations of what to backup.
For the Linux version and Steam it supports normal native Linux games, and it mentions it works with Proton saves too. It will even backup your Steam screenshots. Seems you can run it with the UI or via CLI if you prefer that. Is a game missing? You can just add the saved game details to PCGamingWiki for it to then work for everyone, so even though it uses the data from it they have quite a nice symbiotic relationship.
Not just backing up though, it can restore it all to the right place for you as well. This could be really useful. Hopefully you think so too.
Find it on GitHub.