Tested now. You're right that it's a little more complicated than I hoped it would be.
When I was playing it locally, it worked flawlessly. Now that it's uploaded to browser, it shows
/userfs/godot/app_userdata/Companhita
And I think I need to replace /userfs/ with something that's different per platform (https://docs.godotengine.org/en/stable/tutorials/io/data_paths.html). But the game is aware what platform it's on, so that should be doable.
Just replacing it with %APPDATA% seems to work on windows at least. It automatically finds the right folder.

