Place the chicken breast between two sheets of parchment paper and pound with a meat mallet until it reaches an even half-inch thickness.
In a shallow bowl, soak the chicken in the buttermilk for at least 15 minutes to tenderize.
In a separate bowl, whisk together the almond flour, arrowroot starch, garlic powder, onion powder, paprika, sea salt, and black pepper.
Remove the chicken from the buttermilk, letting the excess drip off, then dredge thoroughly in the seasoned flour mixture until fully coated.
Lightly spray or brush the chicken with avocado oil and place in the air fryer basket.
Air fry at 400°F for 12-15 minutes, flipping halfway through, until the exterior is golden brown and the internal temperature reaches 165°F.
While the chicken cooks, lightly toast the whole wheat bun in a pan or toaster.
Spread the Greek yogurt onto the bottom bun, then layer with the romaine lettuce, tomato slices, crispy chicken, and dill pickles before topping with the other half of the bun.