@pixeldaemon Syncthing. We have one "authoritative" fileserver running syncthing, and then a bunch of "clients" (laptops, phones) that sync up to the fileserver. This doesn't work for, say, terabytes of movies/music, but for important stuff like photos/tax records/whatever, it means we can make changes on any "client" and it gets synced to the "server" and all the other "clients"
For more traditional cloud, I recently installed copyparty (https://github.com/9001/copyparty) w/ https://github.com/romaan7/white-gold-theme-for-copyparty