For a kid his age, there are NU Canon books like
The Mighty Chewbacca in the Forest of Fear (upcoming)
Guardians of the Whills
Smuggler’s Run
Weapon of a Jedi
Moving Target
Before the Awakening (Background for Poe, Finn and Rey)
Cobalt Squadron
The Legends of Luke Skywalker.
They would be more his reading level than some of the other suggestions, great as they are.