TIL about the merge functionality! You can also use Syncthing to synchronise the databases between your devices; if you don't have public IPs for your devices, this essentially means that you can only synchronise when two devices are on the same network -- but this might not be a problem for you.
You can also use Syncthing and the merge function! It comes in very handy when two devices have made changes to the password database file and you end up with merge conflicts :D