Yes, indeed. I didn't understand that at the beginning, and I was very confused.

A couple of examples are

· https://anigma.io/ is an example of a kind of chat room based on Nostr

· https://coracle.social/ is one of a clone of social network owned by the narcissistic ego-maniacal multibillionaire

I haven't stumbled upon a TURN server based on Nostr yet, but I'm sure I will sooner or later. :-)