I recently help family set up their Synology NAS as a photo station and it works fairly well. A dedicated photo folder can be shared amongst users but each use

I recently help family set up their Synology NAS as a photo station and it works fairly well. A dedicated photo folder can be shared amongst users but each user can also have their private repository in their home directory. Pictures are accessed by the NAS webapp or a desicated Photo app on mobile. The app has a fast mode to backup existing files so you can leave it on overnight for the first backup. Downloaded pictures are sorted in year/month folders and it does decent face recognition (not as well as Apple though) and will use geo localisation data for maps and for keywords search of locations. Apple photo data processing is much better at autotagging pictures, and it’s probably going to be difficult or impossible to find something as good, but at least your pictures stay private and remain accessible wherever you are.