Add the broth, squash, apple, onion, celery, and garlic to the Instant Pot. Season with salt, pepper, sage, cinnamon, nutmeg, and cayenne, and give it a good stir.
Close the lid and set the vent to "sealing". Set the Instant Pot to Pressure cooking mode on High (manual) for 8 minutes.
When the timer goes off, hit cancel and carefully turn the vent to "venting" for a quick release. Wait until the steam has released and the valve has dropped, then remove the lid.
Stir in the coconut milk, then use an immersion blender to puree the soup until smooth.*
Add more salt & pepper if needed, and serve hot with your choice of garnish. Enjoy!