I think this was asked by someone already, but I do wonder. I think it would be cool if my sister joined the Fediverse (but blocked NSFW content). She is a high school freshman, but I can’t have her join an instance where you must be an adult.
I do have friends on other social medias that are 13+ with their teen siblings making an account to follow them, but what are the rules here??
I think you should find a smaller, well moderated instance and show it to your parents first. If they consent with her signing up to it, it should be fine and generally speaking there is no practical way for instances to check the age of their members anyways.