Peel and slice the apples, placing them into the Instant Pot. Include the optional fruits as well. Add lemon juice and water. Seal the Instant Pot and turn on the pressure cooker. Set to Manual cook, high pressure, 8 minutes. Be sure the vent is closed.
When the Instant Pot alarms rings after the 8 minute cook time, open the vent to release the steam. Use a thick towel or pot holder to prevent scalding your hand or arm. Open the pressure cooker carefully as there will still be steam rising from the applesauce mixture.
Use a large spoon to mix the applesauce into a smooth sauce. If there are still chunks from apples or the optional extra fruit, use a potato masher or immersion blender.
Allow to cool. Mix in the chia seeds. Using a 1 cup measuring container, scoop a little less than a cup of sauce into the reusable pouch, carefully sealing the package. Place into the freezer for storage until time to hike.