You really inspire me, I will also teach my son about crypto, now he is 2 years old.  I think the way you do I can adapt.  In my opinion, Doge is easy enough for beginners and not too complicated, so it is friendly enough for children.  but with regard to wallets, sometimes I also find it quite difficult to adapt.  better use a mobile wallet which is more user friendly.  At least we teach the concepts to:
1) always record or store keywords / phrases / private key wallets,
2) how to send and receive (related to wallet addresses), 3) explain that there are many types of crypto and cannot be transferred to any address, they must be the same  kind,
4) don't forget to teach how to get it too, haha ​​.. is it too early?