Dolly Parton gets a million points in my book for her Imagination Library. As a parent, it was invaluable to us as a way to provide our child with a revolving door of new books. And as a mail carrier, it makes me glad each time I drop one off. Dolly is GOAT.
No idea regarding Imagination Library having an alternative, even paid, subscription. As for an alternative service, it's not exactly the same but my kid has been enjoying Epic, a kid's reading app for phones and tablets that has subscriptions. Tons of books and many with narration.