Preheat your oven to 375°F. Combine the pulled pork with ¼ cup of the barbecue sauce, stirring until evenly coated, and set aside. Arrange the tortilla chips in a single layer on a large rimmed baking sheet. Scatter half of the shredded cheese over the chips, followed by the pulled pork mixture, half of the diced red onion, and the remaining cheese. Drizzle the remaining barbecue sauce across the top and garnish with jalapeño slices and the remaining red onion. Bake for 8 to 10 minutes, or until the cheese is fully melted and bubbling. Remove the tray from the oven and top with freshly chopped cilantro or any other preferred garnishes. Serve immediately with sour cream and guacamole on the side.