I listened to one of the Audible samples, labeled Virtual Voice. Apple had one labeled as "Madison," so who knows whether they're all going to be labeled so clearly.
It sounded like a TikTok narrator, passable but at the quality level I would expect from a Netflix second-screen show. The book was at the same quality level, too. (The author does "life and business coaching with innovative and adaptable strategies, transcending traditional boundaries.")
I consider these kinds of books and narration to be slop, so I'm definitely not the target market. My worry is that publishers will use AI narrators as virtual scabs to lowball actual creators.