If you haven't already, make the cashew sour cream while the chili is cooking in the Instant Pot.
When the cooking has finished, allow it to sit and naturally release for 5 minutes. Then switch the release knob to venting for a quick release of the rest of the steam. Open the pot, pour the cashew sour cream in and gently stir all together. Salt and Pepper to taste. Serve immediately or allow it to cool and store for later. It lasts for 3-5 days in the refrigerator and longer in the freezer.