Thinking this was carbon steel, I tried to strip it using the canned tomatoes technique, and a lot of elbow grease.
The sides are still black and very hard to clean, but the bottom of the pan reached the metallic color I was expecting. What I didn’t expect though was to discover what looks like a film, either translucent or of a different metallic color, which is starting to strip down although it doesn’t come off easily.
Hopefully the pictures I attached will be good enough.
The main question is "what is this pan made of?", and the bonus question is "can I still restore it to a useable state, or should I just get a new one?"