Cut chicken into 1-inch cubes. Place in a zip-top bag. Add taco and fajita seasoning close tightly and shake to coat all the chicken.
Add oil to a large skillet and heat on medium-high. Add chicken and cook on all sides until browned and cooked through.
Meanwhile, spread tortilla chips to a platter. Layer chicken, pico de gallo, shredded cheddar cheese, and sour cream (black olives, green onions, or any toppings can be added at this point).
Garnish with cilantro and serve.
Notes
See the narrative above for substitutions and tips.