Preheat your oven to 400°F and line a large sheet pan with parchment paper. Toss cauliflower, sweet potatoes, and red onion with half of the olive oil, salt, and pepper. Spread them in a single layer to ensure proper roasting and crisp edges.
In a separate bowl, toss the chicken pieces with paprika, garlic powder, onion powder, salt, pepper, panko breadcrumbs, and the remaining olive oil. After the vegetables roast for about 10 minutes, add the seasoned chicken to the sheet pan. Return everything to the oven and bake until the chicken is fully cooked.
While everything cooks, mix the buffalo sauce and honey in a small bowl. Once the chicken is almost done, drizzle the sauce over the sheet pan ingredients. Toss gently and bake for a few more minutes to allow the sauce to coat and caramelize slightly.
In a mixing bowl, whisk together Greek yogurt, mayonnaise, vinegar, dill, garlic powder, onion powder, salt, and pepper. Add the coleslaw mix and toss until evenly coated. Let it chill briefly in the refrigerator to allow flavors to blend.
Spoon the roasted buffalo chicken and vegetables into serving bowls. Top generously with ranch coleslaw, green onions, and crumbled feta cheese. Serve warm for the best flavor and texture.