Add oil and onion to instant pot and sautee until onions are soft and begin to brown. Add beer, ketchup, broth, honey, vinegar, spices and mustard and mix well. Add roast and spoon liquid over roast if it is not covered.
Place the lid onto the instant pot and seal it shut. Close the pressure release valve. Set the instant pot to manual, high pressure for 55 minutes. When cooking cycle is complete, let pressure naturally release for 10 minutes and then release pressure manually.
Open the instant pot. Very carefully use 2 forks to shred the pork, or remove the pork from the instant pot and shred it on a plate. Return all ingredients to the pot and sautee for an additional 10 minutes until sauce is reduced and thick. Serve on hamburger buns.