Add a Tablespoon or two of olive oil to the Instant Pot and turn it on to saute.
Season Roast on all sides with Salt and Pepper.
When the Instant Pot is hot, sear the Roast in the Instant Pot until browned on all sides.
Turn off the Instant Pot.
Melt butter in a microwave safe bowl or small saucepan on the stove.
Whisk in the Dressing and Gravy mixes along with the pepperoncini juice.
Pour mixture over the top of the roast and top with pepperoncini.
Put the lid on the Instant Pot, making sure the vent is in the sealing position.
Turn the Instant Pot on to the manual setting, high pressure, and adjust the time on the Instant Pot for 60-80 minutes, depending on the weight of the roast. 60 min for 3 lb., 60 min for 4 lb. or 60 min for 5 lb.
After cooking time on the roast is up, allow the roast to naturally release pressure for 10 minutes. This allows the roast to finish cooking.
After 10 minutes is up, vent the Instant Pot to release any remaining pressure.
Once the pressure has been released, remove the roast from slow cooker and cut/shred.