The LOL is telling your Mom about DropbearSSH when this is now how iCloud Photos and Files just works. The equivalent goal is baked in.

You can still use cables or local WiFi via iTunes, but now all media and files sync over-the-air as files, along with an incremental backup of all state.

For the first time in last fall’s iPhone hardware upgrade, I didn’t use a wired backup/restore and every app’s and settings worked, along with device config. I’ve had an iPad Pro unexpectedly need replacing, no wired backup/restore needed. All my stuff syncs across all devices including desktop, all ambiently available.

The life changing part is confidence it’s working to the point of not having to think about it any more.

// Note: Photos and media end up as originals on Mac, along with all files. Those all backup in turn to Backblaze, for loss scenarios not covered by rsync style replication.

That said, I think it might be possible but I think you might have to shim it and wouldn’t have direct access to the file system under the photos.

Open Terminal managed to sandbox a busybox like suite (grep, curl, gzip…). And a scripting language to boot.

rsync limited to the app's directory + shared folders such Photos, iCloud drive, etc would be pretty useful, even without full file system access.

iOS's restrictions are loosening up, vide Files.app