I'm sure grandparent meant to modify it so they'd just have to click "Backup to cloud" on their iPhone and instead of the iPhone sending their files to Apple's servers, it sends them to a local backup server...
Immich can get pretty close to that experience, with the iPhone app and a local immich instance.
A lot of iPhone apps can backup the iOS photo library these days, including the abovementioned Immich, Google Photos, and Dropbox.