Add the chicken breasts to the 6‑quart Instant Pot. Pour in the salsa, chicken stock, chili powder, ground cumin, taco seasoning, lime juice, and lime zest. Season with kosher salt and freshly ground black pepper to taste, then toss to combine.
Close and lock the lid and set the valve to sealing. Cook on high pressure for 10 minutes.
When the cook time ends, perform a quick release according to the manufacturer’s instructions. Open the pot and transfer the chicken to a medium bowl.
Shred the chicken with two forks until it is pulled apart, then taste and adjust seasoning with salt and pepper as needed.
Preheat the oven to 400°F (200°C) and lightly oil a baking sheet.
Arrange the tortilla chips in a single layer on the prepared baking sheet. Top evenly with about 2 cups of shredded chicken (reserve any extra chicken for another use), spoon on pico de gallo, and sprinkle with the shredded cheddar cheese.
Bake in the preheated oven until the nachos are heated through and the cheese is melted, about 10–12 minutes.
Remove from the oven and immediately top with guacamole, sour cream, chopped jalapeños, and chopped cilantro. Serve right away.
