1 hour will be a breeze! For carry on: Take a natural sucker for take off so his ears don't hurt 🍭 pack some favorite snacks and water sippie. You can take a juice or milk box for something different and easy to pack and store. Take a change of clothes just in case. A blanket for changing since the bathrooms don't have pads. Change him before boarding and maybe you can go the whole hour without using the bathroom.
Take a tablet with preloaded movies and headphones or a children's tablet. You can also take a couple light books or a coloring book and a few crayons. Depending on his size and your budget, might be best to get his own seat also. For both of your comfort. Sitting closer to the front of the plane will allow you to exit quicker at landing. Try YouTube for more. Best of luck.