A couple other things to mention, maybe your son is already doing this stuff.
While the trends of Dexcom can be useful, I find the delay between what it shows and my actual BG at that moment to be very impractical during exercise. Dexcom is always a few miles behind. For your son, it might be a few innings behind.
A BG test with a quality meter during every at-bat inning would be extremely useful. And he can look at the change from one inning to the next in the same way you can look at a CGM slope.
I used to use sugar packets with soccer, because if you fall on them it doesn’t cause a problem. Possibly something like that would be useful for when he is out on the field. I think it is better than a hard container of candy or gtabs in your pocket if you land on it. 1 packet has about 4 grams.
I think you said he is a pitcher? That is ideal because he controls the pace of the game. He can take a bit of sugar between batters, everyone is forced to wait for him. He can kick dirt on the mound and adjust his hat or whatever it takes to give him a few moments to take sugar if needed.
Keep in mind a pod can fall off if you land on it. I don’t think you want to fill and activate a pod during a game. He probably already has this, but having a spare pen of insulin in his bag would be a good idea.
I like Gatorade Prime for quick sugar corrections because it is more concentrated than normal Gatorade, and a small sip can give you a very quick boost. They have it on Amazon. It comes in 4 ounce pouches, so he could have a few in his bag for when he is in the dugout.
Strip management for BG meters is the trick. I sent a few strip holders to some people here. They hold strips securely, but allow you to take them out one-at-a-time, even when wearing gloves. It’s much easier than opening a strip vial and spilling them all over. Strips do not fall out of this holder! I use it all the time, every run, and I think it is great. But that’s just my opinion, ask @Michel, @Chris, @ClaudnDaye, @sam, if they are useful for them for different activities.
Here it is
If you want, I can make one for you on my next batch.