Welcome Happy Mommy! I'm sure you'll find great advice here. We have super-smart and allergy-savvy members, who among us are allergic to pretty much everything.
My elder son (who outgrew all his allergies) was allergic to wheat, milk, and soy when he was younger, and I do remember finding portable snack items challenging. I think there are more options now, especially if you check out the gluten free sections of your grocery store (which didn't exist 25 years ago!).
Has he seen a board certified allergist? Which allergy tests has he had? I'm asking because SPT has lots of false positives. What kind of reactions has he had?
Looking forward to seeing you around.