Instant Pot Butternut Squash Soup

Name: Instant Pot Butternut Squash Soup
Ingredients: 4 pounds whole butternut squash (2 medium or 4 small), or 3 to 3 1/4 pounds cut butternut squash; 1 large Granny Smith apple (about 8 ounces); 1 medium yellow onion; 2 tablespoons olive or coconut oil, or unsalted butter; 10 fresh sage leaves, or 1 teaspoon dried sage; 1 (32-ounce) box low-sodium vegetable or chicken broth; 2 teaspoons kosher salt, plus more as needed; 1/4 teaspoon freshly ground black pepper, plus more as needed; 1/3 cup heavy cream or full-fat coconut milk, plus more for serving; 1/2 cup toasted pumpkin seeds, for garnish (optional)