Combine the strawberries, peaches, maple syrup, and lemon juice inside the Instant Pot insert.
Cover the Instant Pot, turn the valve to the sealing (not venting) position.
Set to pressure cook/manual pressure on high pressure for 1 minute.
When done, allow for a natural pressure release.
Open, let cool slightly, and then mash the fruit to your desired consistency.
Select the sauté function and mix in the chia seeds.
Bring the jam to the boil and cook, making sure to stir occasionally for 5-10 minutes, or until it reaches your desired thickness.
Switch off the heat, transfer to a prepared jam jar.