Place the chicken breast between two sheets of parchment paper and pound to 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 small bowl, whisk together the whole wheat flour, smoked paprika, garlic powder, onion powder, sea salt, and black pepper.
Remove the chicken from the buttermilk, letting any excess drip off, then dredge thoroughly in the flour mixture until fully coated.
Lightly spray or brush the chicken with avocado oil and place in the air fryer basket.
Air fry at 375°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 dry pan until warm.
Assemble the sandwich by placing the lettuce on the bottom bun, followed by the crispy chicken and the pickle slices.