In a large bowl, whisk together olive oil, lemon juice, minced garlic, oregano, paprika, kosher salt, and black pepper. Add chicken pieces and coat well. Cover and refrigerate for 15 to 45 minutes.

Chop the cucumbers, cherry tomatoes, red bell pepper, and red onion in a separate bowl. Mix in parsley, feta cheese, lemon juice, salt, and pepper. Drizzle with olive oil and toss to combine.

Heat a skillet over medium-high heat. Add the marinated chicken in a single layer, cooking for 3 to 5 minutes until golden brown. Flip and sauté for an additional 3 to 4 minutes until cooked through.

Warm whole wheat pitas on a griddle for 1-2 minutes. Cut them open and fill each with chicken, salsa, and a dollop of tzatziki. Serve immediately.