Season the chicken: In a bowl, toss chicken with Cajun seasoning, smoked paprika, garlic powder, onion powder, cayenne, salt, and black pepper.
Add 1 tablespoon oil and mix to coat evenly.
Heat the skillet: Place a large skillet over medium-high heat. Add the remaining tablespoon of oil.
Sear the chicken: Add chicken in a single layer. Cook 3–4 minutes per side until browned and nearly cooked through.
Remove to a plate. If using andouille, sear the slices for 1–2 minutes and set aside with the chicken.
Sauté the vegetables: In the same skillet, add onion and bell peppers. Cook 3–4 minutes, scraping up browned bits.
Add zucchini and cook 2 more minutes.
Build flavor: Stir in garlic and tomato paste. Cook 30 seconds until fragrant, then pour in chicken broth to deglaze. Scrape the pan bottom with a spoon.
Finish the skillet: Return chicken (and sausage, if using) to the pan.
Toss with the veggies and simmer 2–3 minutes until the chicken is cooked through and the liquid reduces slightly.
Brighten and serve: Squeeze in lemon juice, taste, and adjust seasoning. Sprinkle with parsley or green onions. Serve hot with extra lemon wedges.