Soldiers train every day in the army. When they are free, they can enrich their brains. A new set of Sun Tzu's Art of War may be a good choice. I don't know if some other youth magazines can be read in the army in spring. If so, they are also good for entertainment. Philosophy books are also very good.
There is also the Long March Feat Stamp Book that is now on sale. It is the first large stamp book produced in the history of stamp issuance in my country. It fully displays the great feat of the Red Army's Long March. It has unique appreciation value and high collection value, and can also let children learn more excellent qualities from the deeds of their predecessors.
There are also some things that your son likes, such as daily use and food. Although it is a bit ordinary and childish, it just shows that only your parents can understand your hobbies so well, and it is your parents who love you the most.