I have found synching to be very useful for making copies of files across devices. I have it setup to mirror photos from my phone, photos from my wife’s phone, and various other things (to-do lists for todo.txt, notes and shopping lists for obsidian… stuff like that) back to my desktop and my NAS. You can set it to do one-way sync (which is more like a backup) or two way sync (where changes anywhere are propagated to everywhere else).

As others have said, it’s not really a true backup solution, but handy to have immediately accessible copies of what’s on your phone in case of phone loss or damage.

For photo viewing and sharing, I am more or less pointing the photo sharing app on my NAS to the photos I sync from phone. They all get dropped into an “inbox” when first synced and then can be organized from there.

You may also want an actual backup solution. There are quite a few and that’s a different topic. The reason I bring it up, though, is that simply mirroring what’s currently on device is not considered a real backup by most people, and for good reason.