Good idea if someday our child have bitcoin, maybe in that time bitcoin is high value, no one tell us, in God will maybe your child become a millionaire.l, just secure your a password and make a take note to your child.
Unfortunately we do not know the future of bitcoin, I think it's too difficult to make sure that bitcoin is suitable given to children, decentralization like bitcoin is only suitable for us who are always active and online so always know the latest updates.