In a bowl, mix Greek yogurt, olive oil, lemon juice, garlic powder, salt, and pepper. Add the chicken and coat well. Let marinate for at least 30 minutes, or up to overnight.
Air fry at 380°F for 18 minutes, flipping halfway through, until fully cooked and slightly golden. Let rest, then slice into bite-sized pieces.
Finely chop the kalamata olives, cucumber, tomato, and red onion. Toss together in a bowl for an easy, fresh topping.
Spread tzatziki onto each tortilla or pita. Add sliced chicken, a generous scoop of the veggie mixture, and finish with crumbled feta.
Wrap it up and dig in! Serve immediately or let everyone build their own for a fun, interactive meal.