Pork roasts include shoulder roast, butt roast, and boneless loin roast. All of these have some fat that adds to the flavor. This fat should also be used to flavor other parts of the meal. So if I am cooking a roast in the oven, I will put sliced or chunked up potatoes with a little bit of water underneath the roast. As the meat cooks, the fat will melt and mix with the potatoes. (I do cover the meat and potatoes with aluminum foil to keep the moisture in. And I typically cook everything at 400F – I think that my stove runs cold and I have found this temp to work well for our kitchen.)
Roasts like these also do well in the crockpot. I put my veggies in the crockpot first. This could include potatoes, winter squash, beans, sweet potatoes, broccoli, or cauliflower (or whatever I have). Then I put the roast in the middle. If it is too high, I make a well in the veggies, so that the meat fits in it and the lid can seal on the top. I put a small amount of water in the bottom to give something to add steam. A lot of these roasts do well with moist heat, and the crockpot lets us provide this.
I don’t have an insta-pot, but it would work in a similar fashion. Follow the manufacturer’s directions.