I've spent a fair amount of time listening to free audiobooks (https://archive.org/details/librivoxaudio) including many that are out of copyright like these, as opposed to modern but in the public domain.
After listening to a few minutes of "Frankenstein" on his site, I would say that these OpenAI generated voices sound better than almost all of the human-read ones on Librevox, both in audio and performance quality -- these are voices that are designed to sound good, and they succeed at that.
Plus, sometimes available human narrations are so bad that you really would like to listen to an AI one (I've experienced it with Churchill's audiobooks on Audible).
I don't know if it will work. It felt like it should work, at least for pSEO.
I got my first two audiobook purchases two weeks after I submitted the sitemap to Google. It was some romantic novels. But now it's flatlined again.
Will see...