App backup? who cares? This was a chance for me to see what's new on F-Droid and it's been great (lookin' at you keyboard.futo.org).
I back up my photos using termux, rsync, and rsync.net. This model seems pretty solid. I should extend it to app data, but I don't have an automated way to back up app data yet. It's just a thing I have to do when I think of it, which is a recipe for disaster.
I'm taking syncthing out of the picture. I was using it to share markdown, html and some graphics between devices and my phone, but I regularly end up diffing .conflict files. I hope to get better behavior from Nextcloud.
Still, I'm the same happy guy I was before December 30 so I think a few manual app data back-ups, back-ups for non-photo content to Nextcloud so I can share it between devices more easily, and the same old rsync stuff for photos should work great.