I recently bought my 11-year-old relative (boy) some small gifts. Here are the ones he liked:
Those stickers with his name on them, with a Japanese cartoon character on them. You order them at bookstores, about 100NT for 150.
Stamp pack from the post office.
Bilingual book of Chinese stories. (He was pretty interested in the Chinese characters and art.)
He put in a request for more stickers, and models of Asian cartoon superheroes.
He didn’t like the t-shirt or the Chinese drum I got, even though he is a drummer. Just didn’t measure up to his own drum-kit I guess.
Hope that gives you some ideas.