Well done for doing some market research before rushing off to code. This is far more sensible than coding first and wondering later.

To answer your question, no. I read a lot and frankly I've never wanted to discuss anything with an author. My relationship is with the characters in the book, not the author.

For non-fiction books there is so much information online that if I want to dig deeper I'll just Google or Chat it.

I've written two text books myself - very (very) niche books that sold in the hundreds of copies. (So very small). I've never had a reader reach out to discuss anything.

Yes, I expect there are people out there who want to correspond with authors. But I suspect a large fraction of them aren't "curious" but more want to demonstrate competence or whatever. I doubt an AI would satisfy them.

Yes, I think there is a market (however thin) for this, but reaching that market will be close to impossible. I would suggest either building this knowing you'd be the only user, or abandoning the idea.