I have an old iPhone 4 with iOS 7.1.2 that I want to backup and sync the photos off of. I have a macOS 10.12, 10.13 and 10.15 device that I was hoping to backup to (if I have to I can try to dig up some older macbooks that might have an older version of OSX on them). For some reason when I plug the iphone 4 in to any device then the iPhone doesn't show up in Finder or iTunes (tho it does draw power from the mac), so I'm not able to make a backup or import the photos.
I'm wondering why the iphone doesn't show up on any macOS device that I plug it in to, and what I need to do to make a backup and/or import the photos?