Place the chicken breast in a shallow bowl and pour the buttermilk over it, ensuring it is fully coated; let it marinate for at least 30 minutes in the refrigerator.
In a separate shallow dish, whisk together the almond flour, 1 tablespoon of arrowroot starch, garlic powder, onion powder, paprika, sea salt, and black pepper.
Remove the chicken from the buttermilk, allowing excess to drip off, then dredge it thoroughly in the seasoned flour mixture, pressing to adhere.
Preheat the air fryer to 375°F and lightly spray the basket with avocado oil.
Place the chicken in the air fryer and spray the top of the chicken with the remaining avocado oil; cook for 15-18 minutes, flipping halfway through, until the internal temperature reaches 165°F and the coating is golden brown.
While the chicken cooks, prepare the gravy by whisking the almond milk, 1 teaspoon of arrowroot starch, and dried thyme in a small saucepan over medium heat.
Continuously whisk the gravy until it simmers and thickens to a velvety consistency, then season with an extra pinch of salt and pepper if desired.
Serve the crispy chicken hot, generously drizzled with the creamy herb gravy.