In a small bowl add sugar, chili powder, cumin, garlic powder, onion powder, paprika, and salt and mix until combined.
Heat grill on high heat. Sprinkle rub on both sides of chicken. Grill tenders 4-5 minutes on each side or until done. Let rest 10 minutes and cut into pieces.
Preheat oven to 400 degrees
Spread 1/4 cup of barbecue sauce on each flatbread. Add 1 cup cheese to each flatbread. Add chicken, onions and pineapple.
Grill or bake for 10-12 minutes or until flatbread is crisp and cheese is melted.
Top with fresh cilantro. Cut into wedges, and drizzle more barbecue sauce if desired.