Slice the chicken breast into even strips or bite-sized nuggets.
Place the chicken in a medium bowl and pour the buttermilk over it, ensuring all pieces are well-coated, then marinate for 30 minutes in the refrigerator.
In a shallow dish, whisk together the almond flour, arrowroot powder, smoked paprika, garlic powder, onion powder, sea salt, and black pepper.
Remove each piece of chicken from the buttermilk, allowing the excess to drip off, and dredge thoroughly in the flour mixture until fully coated.
Preheat your air fryer to 400°F and lightly coat the basket with avocado oil spray.
Arrange the chicken in a single layer in the basket, ensuring no pieces are touching, and spray the tops generously with avocado oil.
Air fry for 10-12 minutes, flipping the chicken halfway through and spraying any dry flour spots, until the crust is golden brown and the internal temperature reaches 165°F.