I used to have a little Java app on an old pre-smartphone which drew a sundial on the screen; point the little arrow at the sun, and the big arrow would point n

I used to have a little Java app on an old pre-smartphone which drew a sundial on the screen; point the little arrow at the sun, and the big arrow would point north. You told it roughly where you were and it used the phone's click to figure out where the sun should be. It worked really well. ...I'd say that modern phones with internal compasses have obsoleted this technique, but given how unreliable phone compasses are, I wonder whether I should try producing an Android version.