Make sure to not pack the meat too tight when rolling into balls. The meat will be too dense and heavy. Roll them gently into balls.
Add all the seared meatballs into the instant pot. Add the tomato sauce to the pot of meatballs. Close the lid and pressure cook on high pressure for 15 minutes . If you rolled the meatballs larger, cooking time will be longer. (These are the steps we did for our Instant Pot: Close the lid and close the Pressure Release Valve. Press "Cancel" to stop the "Sauté" setting. Press the "Manual" button. Set the time to 15 minutes.)