It was easy to share public links to values hosted on the file system in 1995 with Apache. It remains easy today with Nginx and other web servers.
Syncing filesystems across networks with rsync has worked well for years.
If you are considering a personal key value store, you are probably already familiar with web servers and rsync. If not, they are two general purpose tools which are likely to be useful for other projects as well.
I was absent the day of the infamous Dropbox comment.