I would really recommend looking into mini art. All the things you listed are planes but if he likes tanks, they have tanks with full interior that he could spend weeks gluing and painting. Also, if he doesn't already have it, you could buy some thin copper wire for him to add little details to the tanks such as antenna wire, tow cables, wire inside the tank etc. You can also buy the model after market things so he can add detail to the outside of the tank.
AND if you really want him to never come back to reality, you could buy him trees, bushes, solders, barrels, jerry cans, guns, etc so he can make his own diorama.
You said he likes WW2 a lot so below I've linked a couple of interior tanks from WW2. Additionally you can go to their website above and look for other things.
T-34/85 w/D-5T. PLANT 112. SPRING 1944. INTERIOR KIT
ROMANIAN 76-mm SPG TACAM T-60 INTERIOR KIT
Heres a list of all WW2 stuff they have.
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Good luck.