My teen is quite similar to what you’ve described in terms of his interests. Does he have any favourite youtubers that he would want “merch” for? Mine always wants that sort of thing - MatPat is one that he follows who does lots of actually pretty good quality and useful stuff at decent prices (clothes, lamps, board games, storage boxes for gamer stuff etc), and always has good bundles on Black Friday, the only downside is you have to pay extra for shipping from the US (and wait a few weeks for it!) - but I still think it’s worth it including the extra for that, I was actually surprised at the decent quality of his stuff and appreciated that, as he probably could get away with flogging these kids any old tat really.
These days he is often after some sort of game or plushie or model or whatever related to his interests that is being made on Kickstarter (getting the final product does not often coincide with Christmas but he is often just happy to know that it’s been ordered for the future).
He also enjoys things like novelty lights related to his gaming interests like this Tetris light for example:
https://www.amazon.co.uk/Stackable-Interlocking-Lighting-Birthday-Christmas/dp/B0BVG5X78C/ref=asc_df_B0BVG5X78C/?tag=googshopuk-21&linkCode=df0&hvadid=641605173800&hvpos=&hvnetw=g&hvrand=3126375312601547066&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=1007141&hvtargid=pla-2194231368416&psc=1&mcid=aaee6af8cad532bbbcd73b72a016879d
And enjoys collecting those FunkoPop figures of people from his favourite games/movies/TV programmes (a few years ago it was Wandavision for example).
He likes some anime series and I have got him anime drawing books and materials in the past plus an electronic graphics drawing pad thing for that which went down very well.
Redbubble is a great site to find stuff related to their favourite TV programmes etc even if quite obscure! I have got him posters and bedding, mugs etc. from there in the past. Again it’s a US site so bear in mind extra time to shop plus extra cost for shopping/taxes.
My son also loves lots of things from MenKind, their lights, little metal brain game puzzles etc. He had a moving sand art thing from there last year. You can get some of those puzzles and puzzle boxes etc on Amazon too.
He enjoys mentalist type magicians like Derren Brown so has had some books and special cards or other magic trick type things in the past.
Even though he’s probably older than the target age he still loves the Gravitrax marble run thing I got him a couple of years ago.
What about board games? My son loves board games and gets at least one every Christmas. This year I will be getting him the board game of the Traitors TV show (secretly I want it too and so does my sister so we can all play it together lol, his board games every year are often really a present for the whole family that he gets to keep haha).
I often get him one of those laser cut wooden moving model things at Christmas. This sort of thing;
https://www.amazon.co.uk/RoWood-Wooden-Puzzle-Starry-Night/dp/B0B9S5SDVC/ref=asc_df_B0B9S5SDVC/?tag=googshopuk-21&linkCode=df0&hvadid=606811544348&hvpos=&hvnetw=g&hvrand=17166781123619040628&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=1007141&hvtargid=pla-1881583266170&psc=1&mcid=99dce75249063e4aaa0024724b1fdf54#video-immersive-view_1699619958601