Pat the chicken cubes completely dry with paper towels. In a medium bowl, toss the chicken with salt, pepper, garlic powder, and onion powder until evenly seasoned. Sprinkle with cornstarch and toss again to coat each piece lightly.
Preheat your air fryer to 400°F (200°C). Lightly spray the air fryer basket with cooking oil. Arrange the chicken in a single layer, being careful not to overcrowd the basket (cook in batches if necessary).
Air fry for 10-12 minutes, shaking the basket halfway through, until the chicken is golden brown, crispy, and cooked through to an internal temperature of 165°F (74°C).
While the chicken cooks, prepare the glaze. In a small saucepan over medium heat, combine the reserved juice from the can of pineapple, soy sauce, rice vinegar, brown sugar, and ground ginger. Bring to a simmer and cook for 3-4 minutes, stirring until the sugar dissolves and the sauce has thickened slightly.
Transfer the cooked chicken to a large bowl. Add the drained pineapple chunks. Pour the thickened glaze over the top and toss gently to coat everything.
Return the glazed chicken and pineapple to the air fryer basket. Cook for an additional 2-3 minutes at 400°F (200°C) to caramelize the sauce and warm the pineapple.
Serve immediately, garnished with sliced green onions and toasted sesame seeds.