I use nextcloud for syncing between different computers, because I tend to have different machines that are far separated geographically, and it works well. I put all my home folders on each computer into the nextcloud directory so I have all the same files everywhere I go and if I don't have one of my computers I can still log in and access those files.
I used to use nextcloud as my solution for everything, but a big problem with photos is it isn't really very navigable, and a problem with nextcloud as a general platform is everything is a plugin so if the plugin doesn't get updated you can be stuck on an older version of the software which carries its own risks. As well, given the interface, You have your media but you can't really go back and look at it. What I did instead is I set up a library in jellyfin with all my photos sorted into directories, and you can scroll and navigate through them fairly intuitively. I pulled my data out of google and facebook before deleting the accounts and so had many many photos but no way to really enjoy them, but that solution worked really well for me and I've been able to look at my old photos easily.