I would be okay with little kids reading this. I've seen more disturbing children's books in real life.
There is a Little Golden Book now available for the Wednesday Netflix series. Little Golden Books are designed for little kids ages 2-5, and I don't think anyone should watch Wednesday until they're at least 13.
It gets worse. There's even a Little Golden Book called A is for Alien, based on the 1979 Alien movie starring Sigourney Weaver and directed by Ridley Scott. If you won't let your kids see Wednesday, don't let them see Alien either. Alien is much worse.
