01 - Preheat oven to 425°F and line a large sheet pan with parchment paper.
02 - Toss chicken pieces with olive oil, smoked paprika, garlic powder, oregano, salt, pepper, and lemon juice until evenly coated.
03 - Place seasoned chicken on one half of the prepared sheet pan.
04 - Combine red onion, bell peppers, and cherry tomatoes with olive oil, salt, and pepper in a separate bowl.
05 - Spread vegetable mixture on the remaining half of the sheet pan.
06 - Roast for 20-25 minutes, stirring halfway through, until chicken is cooked through and vegetables are tender and slightly charred.
07 - Whisk together mayonnaise, Greek yogurt, parsley, dill, chives, garlic, lemon juice, onion powder, salt, and pepper until smooth and well combined.
08 - Warm pita breads in the oven or on a dry skillet for 1-2 minutes.
09 - Fill each pita with lettuce, roasted chicken, vegetables, drizzle with herby ranch, and sprinkle with feta cheese. Serve immediately.