This has been available in Google Play Books since 2020 in beta and 2022 for any publisher. For a while now, the store has had a large selection of free auto-narrated books whose copyright has expired. As adequate as it is, publishers still pay for real human narrators for bestsellers.

https://9to5google.com/2020/12/03/google-auto-audiobook/

https://www.publishersweekly.com/pw/by-topic/industry-news/a...

https://support.google.com/books/partner/table/10957334?hl=e...