Preheat the oven to 400°F (204°C) and lightly grease a 9x13 inch baking dish with avocado oil.
Prepare the bell peppers by slicing them in half lengthwise through the stem; remove the seeds and white membranes.
In a large mixing bowl, combine the shredded chicken, cauliflower rice, diced celery, and diced carrots.
In a separate small bowl, whisk together the buffalo sauce, avocado oil mayonnaise (or compliant ranch), garlic powder, onion powder, sea salt, and black pepper until fully emulsified.
Pour the buffalo sauce mixture over the chicken and vegetable filling; toss thoroughly until the mixture is evenly coated.
Pack the filling generously into each bell pepper half and arrange them in the prepared baking dish.
Add 2 tablespoons of water to the bottom of the baking dish to facilitate steaming, then cover the dish tightly with aluminum foil.
Bake for 30 minutes with the foil on to soften the peppers.
Remove the foil and bake for an additional 10 minutes until the filling is heated through and the tops are slightly golden.
Garnish with sliced green onions and an optional drizzle of compliant ranch before serving.