I have the same setup, Syncthing + KeepassXC with the add-on: it's not quite as seemless as the Firefox password manager. You have to pair the add-on with the

I have the same setup, Syncthing + KeepassXC with the add-on: it's not quite as seemless as the Firefox password manager. You have to pair the add-on with the KeepassXC program once. Whenever you visit websites that you have saved passwords for, you are asked (via popup) if you want the add-on to fetch the login name and password (because it can handle multiple login combinations for the same websites). Then you have a second click on a small symbol next to the login form which then actually fills in your login data.