> where are the companies that are doing this type of thing for NPC dialogue in games.

"Event[0]"[0] is based on a great implementation of a chatbot NPC/adversary, and there's a nice video by Game Maker's Toolkit explaining how they achieved it [1].

[0] https://en.wikipedia.org/wiki/Event_0

[1] https://youtu.be/bCJw4hQkPj4