eBooks.com

For audiobooks, try Libro.fm (they can sell through or donate to your local bookstore).

Most (mega) publishers list their wares on their sites (e.g. Penguin) and will link out to where you can buy.

I think Apple Books has gotten better (fair) since they got slapped for price fixing on publishers. They’re also looking at AI generated audiobooks as an attempt to compete and pull market share away from Amazon/Audible, as far as I can tell. That’s good for the market perhaps but perhaps raises concerns for pushing not famous voice actor/narrators out of work. A concern about AI overall though, I suppose.

Anyway, my preference for either format is my library online. I recommend that option over anything else.