BBQ Pulled Pork Skillet Nachos

Name: BBQ Pulled Pork Skillet Nachos
Ingredients: 2 whole Large Yellow Onions, Quartered; ⅓ cups Brown Sugar; 1 teaspoon Chili Powder; ½ teaspoons Garlic Powder; ½ teaspoons Salt; 3 pounds Pork Shoulder; 1-½ cup BBQ Sauce, divided; 10 ounces, weight Corn Tortilla Chips; 1 cup White Cheddar Cheese, Grated; 1 cup Monterey Jack Cheese, Grated; 1 can (15 Oz. Size) Black Beans, Drained And Rinsed; 2 whole Jalapenos, Stems And Seeds Removed, Sliced Into Rings; 1 whole Large Avocado, Peeled, Pitted And Cubed; ¼ cups Cilantro, Chopped; ¼ cups Sour Cream, For Dipping; ¼ cups Pico De Gallo (for Dipping)