You could use a language model like gpt-3 for the novel part. In fact, I think that will be the first part of the pipeline that will be of sufficient quality.
I don't really think you could rely 100% on AI for creative things like novels. A fundamental problem with AI (in my humble opinion) is that it simply doesn't have a grasp on reality. Unless if you constantly take care to guide it, it will go off the rails very fast.