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.
People gonna look out for their legal selves. Can’t be mad about that. I moved to avoid the occasional downtimes. Extra benefit that monero doesn’t block these communities. I know they’re hosted in Germany so maybe that’s the difference?