I have volunteered at my kid's school.
My tip:
Just pack what you KNOW your son will eat.
Because... if he does not eat... he will not have anything, in his tummy, from breakfast time and until he comes home. A kid, cannot function like that nor when hungry and without anything in their system. They can get, Hypoglycemic....
I have seen MANY MANY kids who do NOT eat their home lunches... no matter how hungry they are, BECAUSE what is packed for them is not what they like. Hence, they just go without food. That is not good.
Save your "healthy" foods for him at home and once he is home, you can feed him things from across the food-pyramid.
At school and for school, just pack what you KNOW he WILL eat.
If it is the same thing everyday, so what.
Main thing, is that he eats something, at school.
That is a long day to go... without food.
Sure the home lunch can be healthy. I am not saying pack junk food.
Just pack what you know, your son will eat.
Or yes, have him try the school lunches.
My son is picky. At preschool he ate the same home lunch everyday. So what. He ate. It was a sandwich. I explained to the Teachers. No big deal to them. You just EXPLAIN to your son's Teachers.
But at school... my son, now, is eating the school lunches. I know. He tells me and I am often at the school during lunch to help. My kids' school lunches ARE healthy. So of course, I don't mind my kids eating their cafeteria food.
So I KNOW he is eating, there. Not starving since breakfast and until he comes home after school.
Do not worry about making all fancy cutesy buffet home-lunches for him to take to school. Just be practical. Pack what you KNOW he will eat.
I have seen it all.... and all the assorted lunches Moms pack for their kids. But the kid does not eat. Even if hungry.
I even ask the kids why they are not eating their home lunch. And they say "I don't like what my Mommy packed.... I told her what I like. But I don't get that."
Main thing is that your son had food he will eat, at school.
Or a kid cannot concentrate or last, all day without anything in their tummy until they get home from school.
At HOME... is where you experiment and see, with your son, what he will eat for school home lunches.
Don't do this, at school for his lunches... until you know he will eat what you pack.