It works. You either have to link it with your mobile app or you use it standalone with a different user/id

I agree with this comment. As mentioned as answer in the post, to have a backup of these things is a big reason why I chose to selfhost. I had to switch devices (and operating systems) too many times. Moving data around everytime would be a hassle. To have all the important stuff not only stored but also organized and easy to access is very convenient and makes me stop worrying to accidentially lose my phone for example.