In a bowl, combine ground lamb with oregano, basil, onion powder, garlic powder, thyme, fennel, paprika, black pepper, and harissa. Mix until just combined.
Shape into 2-inch patties. Refrigerate 15–20 minutes to firm up.
Line the air fryer basket with a silicone liner or parchment round and spray with cooking spray. Add patties in a single layer.
Air fry at 350°F for 8–10 minutes, flipping halfway, until browned and cooked through.
Check with a meat thermometer — ground lamb is safe at 160°F (71°C).
Warm the pita, then assemble each gyro with lamb, lettuce, tomato, cucumber, red onion, olives, feta, and tzatziki.