I use KeepassXC though, I'm still not terribly confident that I haven't lost data from forgetting to merge another modified database before overwriting it.
In a way, actually. If I use a self-hosted service for hosting the file and keep it open only to myself, then someone who wants that file is targeting me specifically. That's not something I'm particularly worried about. (Obviously someone worrying about that might reconsider this as a line of defense.)
I would actually prefer an even less feature-rich password manager. I've thought of trying to fork something like KeePass for my purposes (or use a restricted subset) but I haven't been willing to devote the time and effort necessary.
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.