Hi merry,
In general most folks avoid the bars and stick to less processed foods with fewer junky ingredients.

So I would make something from sweet treats recipe forum for a "treat."

For the convenience of a bar- I would go with epic. They are basically fancy jerky, but have the convenience of a bar. VT farms makes really nice pepperoni sticks- I'm partial to the ancho turkey variety.

Other easy things to replace bar for your son- pumpkin seeds come in loads of favors, dry roasted edamame are another good snack, baby bel cheese or string cheese travel well, hard boiled eggs, deli slices of turkey rolled up with a pickle spear, celery stuffed with sun seed butter...there are tons of great portable snacks and these will be much healthier than a bar.
You can make chips with melted cheese or flax meal.....
Note- if you use recipe to make cookies that uses peanut butter as a base and sub sunsets butter they will taste great, but turn GREEN when baked.
I would go with something a macaroon instead.