Let the roast rest at room temperature for at least 15 minutes.
Set the Instant Pot to Sauté. When hot, add olive oil.
Season the roast with salt, pepper, and onion powder. Sear on all sides, then remove it.
Pour in beer and scrape up browned bits. Return the roast and sprinkle the au jus mix over it.
Seal the lid and set Meat/Stew for 100 minutes.
Let pressure release naturally for 25 minutes, then vent remaining pressure.
Transfer meat to a plate and shred it.
Set oven to low broil and place rolls on a baking sheet.
Mix butter and garlic powder, brush rolls, and broil 3-4 minutes until golden.
Pile meat on rolls, top with cheese, and broil until cheese just melts.
Top with parsley if using.
Strain the cooking liquid and serve it as au jus for dipping.