I use syncthing to sync my camera folder on my pixel 6a phone with a folder on my NAS.
Then I have an old moto x with pixel experience rom (the rom has unlimited Google photos backup) and syncthing. This phone turns on once a day at night with a smartplug - the folder on my NAS syncs with a folder on phone. The phone backs up the photos to Google photos at full quality.
I'm still mad that Google took away the photo backup for pixel phones. But this seems to work for now
It's still very new but I think it's a great framework to build on. I do worry about fragmentation (each instance having its own gaming community for example). And the smaller niche subreddits I followed will be hard to replace / replicate here.
I am amazed how fast this platform has grown in a few days. Quite exciting!