I think the key is the point where he got excited. Learning can and should be fun, so if you can find a way to teach letters which are more like playing a game, then progress will be much faster and much more pleasant. Sometimes the school way of learning forgets about the enjoyment because they're too busy trying to hit age/grade targets and need to see visable proof in books of the child having that skill. You are doing wonders for your boy trying to find different ways to help him learn! 💚