In a mixing bowl, combine olive oil, oregano, garlic powder, salt, and pepper to create a marinade. Add chicken thighs and mix well. Cover and let marinate for at least 30 minutes.

Heat a skillet over medium-high heat for 2-3 minutes. Remove chicken from marinade and add to the skillet, cooking for 5-7 minutes on each side until golden-brown and internal temperature reaches 165°F (75°C).

In a clean bowl, mix Greek yogurt, crumbled feta, lemon juice, minced garlic, salt, and pepper until smooth. Set aside for flavor blending.

Let the cooked chicken rest, then slice into strips. Warm pita bread, spread a layer of tzatziki, top with chicken and fresh veggies. Roll tightly and serve.