I have a custom GPT for telling my 3 year old bedtime stories. It's super cute to listen to the two of them collaborate back and forth where my kid will add new characters (friends from school, or stuffed animals) and new wacky twists to their adventures, and the storyteller GPT will come up with a new revised version.
It would be pretty rad if she could just have the app on her tablet with a family plan. She doesn't use it quite enough to justify getting her own subscription, but especially if we could share GPTs across devices, so she gets the ones I make for her, but doesn't get flooded with my work or research related GPTs.