I have 2 DDs playing violin, aged 10 and 12, both playing 4 years now.
My girls play Suzuki method, and the parent is expected to be involved.
I have limited musical background. Gave up piano at Grade 4 many many years ago. I never read music fluently, though I can read it at my own pace. And I have a pretty good ear when it comes to tuning.
Talk to his teachers about how you can best support him.
I find my main duty seems to be to remind them to practice, and discuss what to practice. If asked, their teacher gives input into what she would like practiced during a week, and also how she would like certain pieces practiced (e.g. Play the bars with the cords 5 times, the tricky section bars 23-28 5 times, section 3 & 4 a few times, and finally a play through the whole piece...) She might request that DD works on tuning of a particular note. Last week DD2 seemed to be continually hitting G too sharp. So she had a series of notes to practice and to check the tuning of G in that phrase against the tuner on our iPad...
BTW - the tuner on your phone/iPad can be a great help. If there is any arguments about a note being too flat or sharp, that will show you.
Sounds like he is doing great to be reading so well already. And I'm sure his music teachers will be delighted to have you on board supporting him.