I use Syncthing, and a bunch of rsync scripts to keep machines in sync. The stuff I want synced continuously is handled by Syncthing. Other stuff is synced on a daily basis using the rsync scripts and anachron. For Photos, I use PhotoPrism. I simply sync the Photos from all my smartphones to a folder and make PhotoPrism scan it on a regular basis. For cameras though, I need to copy them manually, but I don’t think there’s a way around that.