My Son Energy Crashes During Sport Games

My 9 year old son plays competitive hockey in our area. He is a fit kid (or so I think) with very little fat content on his body. Most practices and games, he is able to last about 40 out of the 50 or 60 minutes before he completely runs out of energy. He seems to recover pretty well but if he has another game that day, he just doesn't have the energy to compete. We have tried high carb meals the night before, as well as the morning of, but that seems to make things worse. Depending on the site you read, you can find such a wide range of opinions, I'm not sure who to believe.

My questions are:

~Are there foods, that help kids in particular, with sustaining energy during competitions?

~What foods are best for kids the evening before?

~Do the energy bars/gummies work? They look like mostly sugar so I'm hesitant.

Thanks for the Help!