Preheat the oven. Preheat the oven to 400°F.
Add potatoes to Instant Pot. Add the potatoes to the bottom of the instant pot. Place the wire rack on top and add 1 cup of water. Set aside.
Combine the ingredients. In a large mixing bowl, combine the beef, pork, onion, red pepper, crackers, milk, ketchup, Worcestershire sauce, sage, and salt. Using clean hands, mix well.
Form the meatloaf and place it into the instant pot. Stack 2 large pieces of tin foil on top of each other and place the meat mixture in the center. Form the foil around the meat into a small rectangular shape. Place the formed meatloaf in the tinfoil onto the wire rack in the instant pot. Place the lid on and turn to seal.
Cook. Set your instant pot to high pressure and cook for 35 minutes. Do a quick release once the time is up. Carefully remove the meatloaf and place it onto a baking sheet.
Add the topping. Using a pastry brush, add brush ketchup lightly onto the top of the baked meatloaf. Bake for 10 minutes.
Remove the potatoes and mash. While the meatloaf is baking, make the mashed potatoes. Drain the liquid from the potatoes and add them to a medium-sized bowl. Add about 1/4 cup of milk and 1-2 tablespoons of butter, along with salt to taste, adding additional milk to get to your preferred consistency.