As a parent I understand that my kid from age 13 was on social media. We actively discouraged it but his friends are on social media so to keep in contact he said he had to be on but we would occasionally check what they were saying, warned him about bullying, knowing everyone in the group etc and limited his mobile phone time. Below 13 I really don’t see a reason for kids to be on social media. Even if their friends are. It’s just I don’t think building a ‘kid friendly’ version of nostr is useful. Kids will use what they want not what we give them.