Cook the Bacon: Turn the Instant Pot to "Sauté" mode. Add the ½ lb (132 g) bacon and cook until crispy, about 5 minutes. Remove the cooked bacon and drain off all but about 2 tablespoons of bacon fat from the pan.
Sauté the Mushrooms: Add 8 oz (225 g) baby bella mushrooms to the pot and cook in the bacon fat until browned and softened, about 5 minutes. Remove and set aside with the bacon.
Sauté the Aromatics: Add a drizzle of olive oil to the pot if needed. Stir in the diced 1 cup (125 g) yellow onion and cook for 3 minutes, until softened. Add 3 cloves garlic and sauté for an additional 1 minute.
Toast the Rice: Stir in 2 cups (360 g) Arborio rice, coating it with the oil and onions. Toast for about 2 minutes, stirring frequently, until fragrant.
Deglaze with Wine: Pour in ½ cup (120 g) dry white wine and stir, scraping up any browned bits from the bottom of the pot. Let it simmer until mostly absorbed, about 2 minutes.
Pressure Cook the Risotto: Add 6 cups (1.4 kg) chicken broth, ½ teaspoon kosher salt, and ¼ teaspoon ground black pepper. Stir well, then turn off the sauté function. Seal the Instant Pot lid and set to high pressure for 6 minutes. The pot will take about 15 minutes to come to pressure, then cook for 6 minutes once pressure is reached.
Release Pressure: Let the pressure release naturally for 7 minutes, then carefully turn the valve to venting to release any remaining pressure. Remove the lid and stir the risotto to combine.
Finish the Risotto: Stir in 2 tablespoons (28 g) unsalted butter, 2 oz (50 g) freshly grated Parmesan, and most of the cooked bacon and mushrooms, reserving some for garnish. Taste and adjust seasoning with additional salt and pepper, if needed.
Serve: Divide into bowls and top with the remaining bacon and mushrooms. Garnish with fresh parsley and extra Parmesan if desired.