i think what device or way will they use it is more important
i rather a static computer where they can sit at a desk and this could be for those in elementary age of 6-12
so that age range is fine.
After the child is intellectually mature enough to correctly answer at least 3 types of questions which ChatGPT obviously can't handle. And to appreciate how ChatGPT just keeps getting those wrong.
That lets the kid really understand how ChatGPT might be a brilliant at spewing BS...but it's still an idiot. And slightly future-proofs them - any new & improved AI, able to answer those types of questions right, probably has other fatal flaws. (But please don't drain your parents' account trying to find those flaws - okay?)