This is a great idea! Recommendation algos are weaponized against kids and would be great to have some way of managing it.
There is a similar problem with movies as well. It is hard to know whether a movie is appropriate for a child e.g. some kind of violence may be acceptable but not adult themes. So marking a movie PG-13 for example doesn't help much. There are some crowd-sourced solutions to this right now such as https://www.commonsensemedia.org/movie-reviews But LLMs could really help automate this