Well, I did make the mashed potatoes in the Instant Pot and they came out excellent!
I used the Yukon Gold potatoes. Put about 1 cup of water in the bottom of the pot and added 1 tsp salt and stirred it. Added my metal steamer thingy and put the potatoes which I just peeled and cut in half on top of the steamer. Cooked 9 minutes and then manual release. Drained the water out and then added butter, salt, milk/cream and just a little sour cream and creme cheese. I DID whip with my hand mixer. They were smooth as silk and yummy. I personally would have eaten them just mashed by hand but for the crowd, whipped them.
Definitely some time saved but also freed up the stovetop. I would do again especially for a big crowd.