Ah, nice! I've been doing something similar to convert web novels --> epub --> mp3/m4b --> sorta a graphic novel --> sorta a video / slide show

Here is pride and prejudice and up the thread you can see another web novel example:

https://twitter.com/HarrisonJackson/status/18109373574214537...

ElevenLabs has so many great voice models but is super expensive. I want to experiment with some oss voice models and even train my own but not sure on a great starting point with that. Play.ht has some good voices, too.

Seeing some of the results here with the openai tts I will probably switch at least the narrator to use one of these to save some money.