Add chicken, salsa, chicken stock, chili powder, taco seasoning, and cumin, lime juice, and zest, to a 6-qt Instant Pot and toss to combine. Season with salt and pepper.
Close and lock the lid, point the valve to sealed (on older models).
Cook on high pressure for 10 minutes. When finished cooking, do a quick-release according to the manufacturer’s directions.
Remove chicken from the Instant Pot and place it in a medium bowl. Shred-it using two forks, and season it with salt and pepper, to taste.
Make nachos:
Preheat oven to 400 degrees F. Lightly oil a baking sheet.
Arrange the tortilla chips in a single layer onto the prepared baking sheet, and distribute them evenly.
Top with 2 cups of shredded chicken (reserving the remaining chicken for later use), pico de Gallo, and shredded cheese.
Place into oven and bake until heated through and the cheese has melted; about 10-12 minutes.
Serve immediately, topped with guacamole, sour cream, sliced jalapenos, and cilantro.