Probably a satellite in low-earth orbit. They only take a few minutes to go from one horizon to the other. Since it is very bright, I am guessing it is the ISS.
Update: Iceland is too far north (64°N) to see the ISS (max 51.6°N). Too bad.
Update: Iceland is too far north (64°N) to see the ISS (max 51.6°N). Too bad.
Edit: or based on the fireball timing, mister detective here just realised. The comments even say "Is it possible that it was on 12.09.2023 at 22:35? We were in Höfn watching the northern lights when we saw it" and a reply confirms it