Press the "Sauté" button on the Instant Pot. Add the olive oil and onions, and sauté until softened, about 5 minutes. Add the zucchini and mushrooms and sauté until the mushrooms have begun to soften and give up some of their liquid, about three more minutes.
Add the pasta sauce and water to the Instant Pot and stir to combine.
While the sauce is coming up to a simmer, make the meatball mixture. In a medium mixing bowl, combine the ground turkey, rice, Italian herbs, and salt. Mix well and roll into a dozen meatballs, a little larger than golf ball-sized.
Gently drop the meatballs into the simmering sauce in the Instant Pot, spooning a little sauce over the top of each one.
Press the "Keep Warm/Cancel" button, then select the "Poultry" setting. Put the lid on the Instant Pot, making sure the pressure valve is set to "Sealing."
When the program has finished, the Instant Pot will beep to let you know dinner is ready! You can serve them right away, but they will also keep warm in the pot for up to 10 hours automatically.
Top with fresh basil (optional) and serve.