I opened this thread, as I really like the idea to have a foss backup method that works similar to googles native cloud backup system, but where the user can specify their own cloud server (eg. Nextcloud) as backend.
While exploring my phone (AOSP), I stumbled across a nearly empty “backup” section in the settings.
I think that on a google phone, this section has settings for google cloud backup. I did some research and found AOSPs BackupTransport class. I have the strong feeling, that googles backup mechanism must be an implementation of that class.
It would be really cool if somebody could create an app, that transparently creates regular full app backups onto a slfhosted cloud, the same way google backup does. Unfortunately I don’t have enough time to do this, but maybe someone finds this a cool idea as well
Edit: I think that such an app would require to either be installed as a system app, or require to be run as root. Still, in my opinion it would be a great addition to the foss android environment.