In the Instant Pot, place the pumpkin and apples.
Using Manual mode, set timer to 10 minutes.
Allow to cook and natural release for 10 minutes.
You may release any remaining pressure after that.
Open the Instant Pot and add the remaining ingredients.
With a stick blender, blend until smooth.
(Or, you may use a food processor or high-speed blender to smooth the sauce)
Once, cool, package into jars and store in the refrigerator for up to two weeks or freeze for longer storage.