Slice the chicken breast into even-sized strips or medallions.
Place the chicken in a bowl and pour the buttermilk over it, ensuring every piece is coated; marinate for at least 20 minutes.
In a shallow dish, whisk together the whole wheat flour, smoked paprika, garlic powder, onion powder, sea salt, and black pepper.
Remove each piece of chicken from the buttermilk, letting excess drip off, then dredge thoroughly in the flour mixture.
Lightly spray the air fryer basket with avocado oil and arrange the chicken in a single layer without crowding.
Air fry at 400°F for 12 to 15 minutes, flipping halfway through, until the coating is golden and the internal temperature reaches 165°F.
While the chicken cooks, whisk the chicken broth and arrowroot powder in a small saucepan over medium heat until it begins to simmer and thicken.
Remove the sauce from the heat and whisk in the Greek yogurt until completely smooth to create the gravy.
Drizzle the warm gravy over the crispy chicken and serve immediately.