Generously season the roast on all sides with salt, pepper, garlic powder, and onion powder.
Add the roast to the Instant Pot.
In a bowl, mix together gravy mix packets, Worcestershire sauce, and beef broth.
Pour gravy mixture in the bottom of the Instant Pot (try to not wash the seasonings off the roast).
Place the lid on top of the Instant Pot. Move valve to SEALING (not venting).
Press MANUAL (or PRESSURE COOK) button and set timer for 40 minutes for a 2 pound roast or 60 minutes for a 3 pound roast (about 20 minutes per pound of meat).
When cooking is done, allow roast to do a natural release (at least 30 minutes - the longer you can let it sit, the better. Sometimes I will let a roast stay on KEEP WARM for a few hours).
Remove lid and remove roast from Instant Pot, then shred using 2 forks (it should fall apart fairly easily).
Stir the gravy left in the pot (it should have thickened up a little bit during cooking time, but if you want it to be thicker, you can mix together 1 teaspoon cornstarch and 1 teaspoon water and then add it in to the gravy and stir until it thickens up).
To serve, place some shredded roast on top of a thick slice of bread and then top with gravy (like an open-face sandwich).
Notes
To make this into a freezer meal:
To make this into a freezer meal, season roast with salt, pepper, onion powder and garlic powder and add to a gallon-sized freezer bag Mix together gravy packet, Worcestershire sauce, and beef broth. Put freezer bag into freezer and it will last up to 90 days. When ready to use, dump ingredients from bag into Instant Pot and add 1/3 cup of water in with the frozen food. Place the lid on top, move the valve to SEALING, and press the MANUAL (or PRESSURE COOK) button. Set timer for 75-120 minutes (35 minutes per pound of roast) . Let the roast do a NATURAL RELEASE when the timer is done. Follow the rest of the instructions as written.