Help with persistent Android port save files

[Filipis]

I am asking for help (in a "simple" guide format") in figuring out how to add persistent save files for android ports of Renpy games, such that their saves 'transfer' between apk updates. This could take the form of simply moving the save file location to an external location (outside of the game folder), so that uninstalling the game does not delete them. I literally can't find any such guide existing, without using modified Renpy launchers - it's not that demanding, is it?