Cut the chicken breasts into small, bite-sized pieces and place in a bowl.
Season the chicken with garlic powder, paprika, chili powder (or cayenne), and black pepper; toss to coat evenly.
Place the seasoned panko in one shallow bowl and the hot sauce in another bowl.
Working in batches, dip a few chicken pieces into the hot sauce to coat, then dredge in the panko to fully coat each piece.
Arrange the coated nuggets in a single layer in the air fryer basket without overcrowding; repeat for remaining pieces.
Spray the tops of the nuggets generously with olive oil spray, air fry at 400°F (200°C) for 8 minutes, flip the nuggets, spray the other side, then air fry an additional 8 minutes until golden and cooked through.
Serve the buffalo chicken nuggets with celery, carrot sticks, and blue cheese dressing if desired.