Turn your Instant Pot to the “SAUTE” function and add a drizzle of olive oil to the inner pot. Add the ground beef, diced onion, seasoning salt, black pepper, and garlic powder to the pot. Using a hamburger chopper, break up the ground beef. When the hamburger is broken up and mostly browned, add 3/4 cup water to the pot. Using a wooden spoon or spatula, scrape the bottom of the pot to remove any browned bits. Sprinkle one cup of brown rice over the water and hamburger mixture and do NOT stir it together. Top the rice with the Worcestershire sauce, mustard, and two cans of diced tomatoes, being sure to cover all the rice with tomatoes. Place the lid on the Instant Pot, lock it in place, and move the knob to seal. Cook on high pressure for 10 minutes. Allow the pressure to naturally release for 10 minutes after the cooking time is complete. Carefully turn the knob to vent to release any additional pressure. Using a fork, mix the beef and rice mixture. Top with shredded cheese and place the lid back on the pot for 2-3 minutes to allow the cheese to melt. While the casserole is cooking, in a small bowl, mix the special sauce ingredients. Serve the casserole with the sauce and chopped pickles on the side. Enjoy!