Preheat oven to 425°F. Line a sheet pan with parchment paper or aluminum foil.

Cut chicken breasts into 1-inch cubes. In a large bowl, combine brown sugar, smoked paprika, garlic powder, onion powder, cayenne, and salt. Add chicken and olive oil and toss to coat. Add lemon slices and toss gently.

Spread chicken and lemon slices in a single layer on the sheet pan. Roast for 15 minutes without stirring, then toss and roast another 5-7 minutes until chicken reaches 165°F and has caramelized edges.

While the chicken roasts, whisk together yogurt, dill, parsley, chives, lemon juice, olive oil, and salt in a large bowl. Add thinly sliced cabbage and toss to coat. Let rest 10-15 minutes.

Warm pita pockets in the microwave 20-30 seconds wrapped in a damp paper towel. Cut open each pita pocket.

Stuff each pita with a generous amount of slaw, then chicken pieces and sliced avocado. Drizzle with pan juices and optional hot sauce or feta.