The only problem I foresee in doing this is adding every possible save location for games. They seem to save all over the place, so finding out the right directory to sync for each game is extremely time consuming.
I wanted to do this before, but gave up. If you want to only sync the game saves and not a ton of unrelated data, it’s a chore.
Even tools like ludusavi don’t have directory’s added by default for anything non Steam due to this.
If anyone has a good solution to this, I’d love to hear it!