Place the chicken thighs in a bowl and pour the buttermilk over them, ensuring they are fully coated, then marinate for at least 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 until well combined.
Preheat your air fryer to 400°F (200°C) for 5 minutes.
Remove each chicken thigh from the buttermilk, letting the excess liquid drip off, and dredge thoroughly in the flour mixture until evenly coated.
Lightly grease the air fryer basket with half of the avocado oil to prevent sticking.
Place the chicken in the basket and drizzle or spray the remaining avocado oil over the tops to ensure a golden, crispy finish.
Cook for 18 to 22 minutes, flipping the chicken halfway through, until the internal temperature reaches 165°F and the exterior is golden brown.