Audible is offering various children’s books/stories for free in English, French, German, Italian, and Chinese (there could be others, but these are what I found) due to kids being stuck at home during the Covid-19 pandemic.
You don’t need an Audible account to listen. Just click on the book and it will start playing (web site version).
A few adult books seem to have slipped in, for now at least. I’m currently listening to Portrait of Dorian Gray in French for free and that’s definitely not a children’s book!