I don't think he'd be too small for superworms, a little leopard gecko I used to have could down them and adult dubia roaches, and a female fire skink about 7 inches I had could down superworms too. They just crunch them up and it may be a good extra source of protein.
Superworms also come in smaller sizes, and they grow pretty slow.
Large amounts of mealworms can be bad for babies, because they have more shell to meat ratio, but they are okay to feed adults.
I usually make a salad, put a few supers and mealworms in with the salad and stick it in a dish the mealies cant crawl out of and it's like a nutricious buffet
Also, sand is not good for young Beardies, they have been known to injest it accidentaly and on purpose and become impacted. If you feed in the tank live bugs on the sand, you want to stop that and feed in separate container. Even the calci sand does not break down in the animal like it says on the bag. Very dangerous stuff. Best to go with tile, paper towels, or reptile carpet and wait until they are a full adult to give them sand.
Or for my stupid Beardie, no substrate, he eats the paper towels, his fake plants, and chews on his rocks after I wash them...He really is a very special big guy.