Super cool game idea, I can't imagine how long it may have taken you. I'm not too familiar with how openAI works with unity, etc, so I'm not sure if this is even doable, but it would be cool if you were able to make the voice of the NPC be your voice like how it was when you open the game (Though I imagine you would have to record yourself and create a massive word bank amongst all the other things that you would have to do).
I think including more into the scenes would be beneficial as well, but I really like what you have done so far. It's super unique.