Place the chicken breast between two sheets of parchment paper and pound to an even half-inch thickness.
In a shallow bowl, submerge the chicken in the buttermilk and let marinate for at least 15 minutes.
In a separate shallow dish, whisk together the whole wheat flour, garlic powder, smoked paprika, sea salt, and black pepper.
Remove the chicken from the buttermilk, allowing excess to drip off, then dredge thoroughly in the seasoned flour mixture.
Preheat your air fryer to 375°F and lightly coat the air fryer basket with the avocado oil.
Place the chicken in the basket and air fry for 12-15 minutes, flipping halfway through, until the exterior is golden and the internal temperature reaches 165°F.
While the chicken cooks, lightly toast the sprouted grain bun in a dry pan over medium heat.
Assemble the sandwich by placing the lettuce on the bottom bun, followed by the crispy chicken and the dill pickles.