Preheat air fryer to 400°F (200°C).
In a large mixing bowl, toss the cubed chicken and halved Brussels sprouts with olive oil, salt, and black pepper until evenly coated.
Place the chicken and sprouts in the air fryer basket in a single layer, working in batches if necessary to avoid overcrowding.
Air fry at 400°F for 15 to 18 minutes, shaking the basket every 6 minutes to ensure even browning and crisping.
While the chicken and sprouts cook, whisk together the sweet chili sauce, soy sauce, grated ginger, and minced garlic in a small bowl.
Verify that the chicken has reached an internal temperature of 165°F and the sprouts are tender with charred edges.
Transfer the cooked chicken and sprouts to a clean bowl, pour the prepared sauce over them, and toss to coat thoroughly.
Garnish with sesame seeds and sliced green onions before serving immediately.