Season chicken with lime juice, ½ teaspoon salt, chili powder, cumin, dried oregano and smoked paprika.
Add 1 tablespoon canola oil to a 12-inch skillet over high heat.
Add bell peppers and onions to the skillet and season with ½ teaspoon salt. Cook until charred and softened about 6 minutes, stirring occasionally.
Transfer to a large bowl.
Add remaining 2 tablespoons oil to skillet.
Add chicken to the skillet and cook until browned and cooked through, about 5 minutes, stirring occasionally.
Add cooked peppers and onions and garlic back to the skillet with the chicken. Cook until garlic is fragrant, about 30 seconds. Remove from heat and set aside.
Set oven to broil and line a sheet pan with parchment paper.
Spread chips in an even layer on the baking sheet.
Evenly sprinkle with half of the cheese.
Top with the chicken fajita mixture and remaining cheese.
Broil until the cheese is melty, bubbly, and browned around the edges, about 8 minutes.
Once the nachos are done top with guacamole, sour cream, and cilantro. Serve immediately.