Heat oil in Instant Pot over “browning” setting. Season shoulder roast with salt and pepper. Brown on all sides, then remove and set aside. Saute garlic and onion in Instant Pot for 2 to 3 minutes.
Rub remaining seasonings all over roast (cumin through onion powder). Place back in Instant Pot, and add all remaining ingredients (broth through bay leaf).
Cover and cook using the pressure cooker setting, put it on high pressure and set the meat button to 50 minutes. After 50 minutes, release pressure and slowly remove lid. Shred with two forks and make sure it’s all saturated in its cooking juices. Remove bay leaf before serving.