Preheat the oven to 375°F and line a sheet pan with parchment paper or lightly grease it.
In a large mixing bowl, add the diced chicken, olive oil, paprika, garlic powder, onion powder, chili powder, oregano, cumin, salt, and black pepper. Mix until the chicken is evenly coated.
Add the minced garlic, sliced bell peppers, and sliced red onion to the bowl and toss until everything is well combined.
Spread the chicken and vegetables evenly across the prepared sheet pan in a single layer.
Bake for 30 to 35 minutes, or until the chicken is fully cooked and lightly browned, stirring once if needed for even cooking.
Warm the gluten free tortillas according to package directions.
Assemble the fajitas by adding the chicken and vegetables to each tortilla, then top with lime juice, avocado, sour cream, mozzarella, and chopped cilantro as desired.
Serve warm.