Besides Basic English, I've run into a neat French dictionary for children, https://www.amazon.com/Mon-premier-dictionnaire-Roger-Pillet...

It sticks to a basic vocabulary, has an entry for every word it uses, and goes heavy on examples and pictures in preference to formal definitions. (And it's monolingual even though written mainly for learners in North America.)

I don't have it to check, but estimating from memory: around 2000 to 4000 words. I found it useful while bootstrapping up from Duolingo.