Pound the chicken breast to an even thickness of about half an inch.
Place the chicken in a bowl and cover with buttermilk, marinating for at least 15 minutes.
In a separate shallow dish, whisk together the almond flour, arrowroot, paprika, garlic powder, onion powder, salt, and pepper.
Remove the chicken from the buttermilk and dredge it through the flour mixture, pressing firmly to ensure the coating adheres.
Lightly spray both sides of the coated chicken with avocado oil.
Place the chicken in the air fryer basket and cook at 375°F for 12-15 minutes, flipping halfway through, until the coating is golden and the internal temperature reaches 165°F.
Toast the sprouted grain bun in a dry pan until the edges are lightly browned.
Assemble the sandwich by layering the lettuce, crispy chicken, and pickles onto the toasted bun.