Wow he's just over a couple years my junior!
I would see if there's any accessories to help facilitate, like maybe he's been making do without a headset/microphone or maybe an extra hard drive?
(Those come to mind right now because I could use a mic for my PC for those team games and I've been procrastinating on getting one but if he doesn't have one, it adds a lot to the experience.
Last year my roommate and I plugged in a hard drive of mine to his Xbone to make room for some extra games, I'm still surprised how much space they can take frankly, but I don't know if he's rolling in storage or not.)
Smaller gifts could also be related merch like branded stickers, art, figurines, clothing depending.