Season chicken thighs with smoked paprika, garlic powder, salt, and pepper.
Cook chicken in olive oil over medium-high heat, 5 to 6 minutes per side, until cooked through to 165°F.
Rest the chicken 5 minutes, then slice.
Combine cabbage and red onion. Whisk mayonnaise, vinegar, honey, and salt, then toss with the cabbage. Let sit 10 minutes.
Warm the flatbreads in a dry skillet or low oven until pliable.
Top each flatbread with chicken, slaw, feta if using, and fresh herbs.
Serve immediately with lemon wedges.