Add all sauce ingredients (brown sugar, vinegar, soy sauce, ketchup, garlic powder, salt) to a small pan over medium/low heat. Stir together and bring to a slight boil. Allow it to simmer for 5-10 minutes
Meanwhile, cut chicken tenderloins up into bite size pieces, about 1 inch by 1 inch
Place cornstarch on a plate and season with the chicken seasonings (salt, pepper, garlic powder, onion powder and one very small pinch of cinnamon), stir together. One by one, add chicken pieces to the plate and roll around plate until evenly coated
Once all the chicken nuggets are coated, place in the greased air fryer and air fry for 1 minute. Spray chicken with cooking spray then air fry for another 3 minutes. Flip/shake the chicken and spray with cooking spray again. Air fry for another 4-6 minutes, or until thoroughly cooked.
Chop up the vegetables into bite sized pieces. Grease a small pan with cooking spray and heat up over medium/high heat. Add vegetables and sauté until slightly soft
Meanwhile, combine slurry ingredients (corn starch and water) in a small bowl, stirring to remove any clumps. Once sauce has finished simmering, slowly pour in slurry until desired thickenss is reached
After everything is cooked, add chicken and vegetables to the pan with the sauce and toss to evenly coat