Preheat the air fryer to 375°F (190°C).
Slice the banana peppers in half lengthwise and remove the seeds.
In a mixing bowl, combine the cooked rice, shredded cheddar cheese, cooked ground beef or turkey, diced onion, garlic powder, paprika, salt, and black pepper. Mix well until all ingredients are evenly combined.
Stuff each banana pepper half with the filling mixture, pressing down gently to pack it in.
Brush the stuffed peppers with olive oil to help them crisp up during cooking.
Place the stuffed peppers in the air fryer basket in a single layer. Cook for 10-12 minutes, or until the peppers are tender and the cheese is melted and bubbly.
If desired, drizzle marinara sauce over the stuffed peppers before serving.