Preheat a 6-quart air fryer to 390°F for 3 minutes. Pat the thighs thoroughly dry, especially the skin, and unfold them without removing the skin.
Rub the meat sides with lemon zest, pepper, garlic powder and half the salt. Rub the skin lightly with oil and remaining salt.
Place skin-side down in the basket and air fry for 7 minutes. Turn skin-side up and cook for 8 to 11 minutes more until the skin is crisp and the thickest meat reaches at least 165°F.
Transfer skin-side up to a plate and rest uncovered for 5 minutes. Spoon lemon juice around the cut meat edges rather than over the crisp skin.
Serve one thigh per person while the skin is still crisp.