Select saute function on instant pot and set to normal. Add butter and oil; stir until butter melts, about 2 minutes. Add mushrooms; cook, stirring occasionally m until slightly softened, about 3 minutes. Stir in onion and cook 2 minutes. Add rosemary and cook 1 minute more. Stir in the rice until the grains are coated. Stir in broth, wine, and S&P.

Close and lock lid; turn venting knob to seal. Select high pressure and set timer for 6 minutes. Allow 10 to 15 minutes for pressure to build.

Release pressure using quick release method and carefully remove the lid. Stir risotto until creamy, about 1 minute. Discard the rosemary stem. Stir in 1/2C parmesan until melted and combined. Season to taste with additional S&P. Top the servings with the remaining 1/4C parmesan and toasted nuts.