That's possible with KeePassXC (desktop) [0], KeePassDX (mobile) [1] and Syncthing [2]. Best thing about it is that the bridge between devices is also end-to-end encrypted, which is a nice bonus if you want to sync something else. I wish there was an easier all-in-one application for this kind of stuff though, would be much easier to maintain and setup for family/friends.

[0]: https://keepassxc.org/

[1]: https://www.keepassdx.com/

[2]: https://syncthing.net/