Found by trial and error... apparently you need to double sign up.

The error I got was "cannot sign in". This came from stacker news as I wans't signed up. This seems "obvious" for us, but not for end users.

Once you're logged in to keychat and then go to stacker news, you can assume your nostr account gives access to such services.

The small "signup" option I tried just to see if the interaction was going ok, sloved the problem, as then the stacker news signup allowed me to log in with extenstion from keychat itself. So, not your side , but the interaction between services on nostr and user-expecations.

(might sound dumb, but I see nostr login as a way to login, like "login with google"... so the fact that I need to signup on services before that works, seems odd