Place the chicken breast in a small bowl with the buttermilk and marinate for at least 20 minutes in the refrigerator.
In a separate shallow dish, whisk together the whole wheat flour, smoked paprika, garlic powder, onion powder, sea salt, and black pepper.
Remove the chicken from the buttermilk, allowing any excess to drip off, then dredge it thoroughly in the flour and spice mixture until well coated.
Lightly brush or spray the coated chicken with avocado oil and place it in the air fryer basket.
Air fry at 375°F for 15 to 18 minutes, flipping halfway through, until the exterior is golden brown and the internal temperature reaches 165°F.
While the chicken cooks, steam the broccoli florets and boil the sweet potato until tender, then mash the sweet potato until smooth.
Serve the crispy chicken immediately alongside the fluffy mashed sweet potato and steamed broccoli.