Set the Instant pot to Saute and add the oil, butter, and garlic. Scrape the bottom to deglaze the pot. Any stuck on bits on the bottom of the liner can result in a "burn" notice. Break the fettuccine, fan it out evenly in the pot.
1Layer the tuna over the pasta. Add the lemon juice and zest. Sprinkle in the salt and the pepper Pour in the 2 cups of broth - do not stir.
Close the lid and pressure cook on HIGH using the PRESSURE COOK/MANUAL setting for 4 minutes. Carefully perform a quick release to relieve the pressure by turning the steam release knob to the venting position. Do this slowly to prevent steam or water from spewing from the valve.
Open the lid, add in the heavy cream, and stir. Toss with baby spinach and capers, and serve with fresh parsley and dill.