I've read a lot here about the problems with Seedvault and I can't get a reliable automatic backup with Seedvault myself. But an OS without a reliable automatic backup is worthless to me.
I've also read here that programming a new backup app would be very time-consuming and it's not clear where the man-power would come from.
But why to programm something completely new?
My suggestion is therefore to integrate Restic (https://restic.readthedocs.io/en/stable/).
I use Restic as backup software for all my private and office computers.
It supports lots of repositories (local systems, SFTP, Amazon S3, Backblaze B2, Azure, Google Cloud and much more), strong encryption and there is an Android app (https://github.com/lhns/restic-android).
I haven't tested the Android app yet, as it naturally doesn't have access to all the necessary directories under Graphene to realise a complete backup, but that should be possible and not involve too much effort, right?
What do you think?