Pat chicken breast pieces dry with paper towels to remove excess moisture.
In a shallow bowl, combine cornstarch, salt, and white pepper.
Place beaten egg in a separate bowl. Dip chicken pieces first in egg, then coat in cornstarch mixture.
Let coated chicken rest for 5 minutes to help coating adhere.
Preheat air fryer to 380°F for 3 minutes.
Lightly spray air fryer basket with olive oil. Arrange chicken in a single layer and spray tops lightly with oil.
Cook chicken for 10 minutes at 380°F, shaking basket halfway through. Chicken should reach 165°F internal temperature.
While chicken cooks, combine pineapple juice, rice vinegar, brown sugar, ketchup, soy sauce, sesame oil, ginger, and garlic in a small saucepan.
Bring sauce to a gentle simmer over medium heat. Whisk in cornstarch slurry and simmer 2-3 minutes until thickened. Remove from heat.
Place bell peppers, pineapple chunks and onion in air fryer basket. Air fry at 380°F for 4 minutes until slightly tender but still crisp.
In a large bowl, combine cooked chicken with vegetables. Pour two-thirds of the sweet and sour sauce over mixture and toss to coat.
Return sauced chicken and vegetables to air fryer. Cook at 380°F for 2 minutes to caramelize sauce.
Serve immediately with remaining sauce on the side.