Keepass is great at syncing itself and merging conflicts (although I don't know how it works exactly so it makes me nervous), but it requires you to have a shared platform if you want access to it on multiple devices.
You can use a cloud, but at least on my GrapheneOS phone and Linux laptop with a desire to use open source code as much as possible, the UX is terrible and it requires user accounts too.
Syncthing is supposed to be good, but I never got it to work properly.