Make the tzatziki sauce if needed and prep all vegetables and toppings: halve tomatoes, slice cucumber, chop bell pepper, dice avocado, thinly slice red onion, pit and slice olives, and dice feta.
Marinate the chicken: place the chicken cutlets in a large zip-top bag with 2 Tbsp olive oil, dried oregano, 1/2 tsp salt, 1/2 tsp pepper, and 1/2 tsp garlic powder; seal and toss to coat evenly.
Preheat a grill or large skillet to medium heat.
Cook the chicken: grill or sauté the cutlets 4 to 5 minutes per side, until an instant-read thermometer reads 165°F at the thickest part.
Rest and slice: transfer chicken to a cutting board and let rest 10 to 15 minutes, then slice into bite-sized pieces.
Assemble bowls: divide chicken, tomatoes, cucumber, bell pepper, avocado, red onion, olives, and feta among 4 bowls.
Finish and serve: drizzle bowls with the remaining 1 Tbsp olive oil, squeeze lemon wedges over top, season with salt and pepper to taste, add tzatziki, and serve with pita wedges.