"I back up my photos using termux, rsync, and rsync.net. This model seems pretty solid."
This is a common workflow.
In addition to termux/rsync we do see a number of people using syncopoli.
FWIW, my personal phone is an iphone and I use the excellent 'iexplorer' to browse the phone as if it were a filesystem.
I wrote a how-to!
https://troyvit.net/2023/01/backing-up-android-to-rsync-net/
It has one error. termux-job-scheduler isn't a separate install.
One extra tip is to use rrsync to restrict which folders your rsync client can read/write to: https://b.tuxes.uk/termux-rsync-photos.html
This helps mitigate ransomware, and escalation (e.g. reading previously backed up files) attacks.
Can you share resources on how to backup through termux? I hadn't thought of that.