In a skillet, heat the olive oil over medium heat. Add the diced chicken, oregano, garlic powder, salt, and pepper. Cook until the chicken is cooked through, about 7-10 minutes.
In a small bowl, mix together the Greek yogurt, lemon juice, garlic, and salt.
To assemble, cut the pita pockets in half and fill each with the cooked chicken, cherry tomatoes, cucumber, red onion, olives, and feta cheese. Drizzle with the yogurt sauce and garnish with fresh parsley.