Preheat oven to 425ºF (220ºC). In a bowl, combine chicken with brown sugar, smoked paprika, garlic powder, onion powder, cayenne pepper, kosher salt, and olive oil. Toss to coat and add sliced lemon.

Spread the chicken mixture onto a sheet pan in a single layer and roast for 15 minutes. Toss chicken for even cooking and roast for another 4 to 7 minutes until fully cooked.

In a bowl, whisk together yogurt, dill, parsley, chives, lemon juice, olive oil, and salt. Fold in shredded cabbage and let rest for 10 to 15 minutes.

Warm pitas in the oven for about 2 minutes. Fill each pita with slaw, roasted chicken, and avocado slices to serve immediately.