Unless you follow the advice of cooking the sauce for a couple of hours, after which all that will be left of the veggies will be basically fiber.

To be fair, when cooking a sauce (or stew, soup etc.), some of the nutrients will enter the sauce (vs. cooking water that will later be thrown away), but preserving nutrients / vitamins etc. while cooking still means reducing heat / cooking time.

Please don’t cook vegetables to oblivion and assume this will fulfill your kids nutritional needs. Not talking about you in particular, just making sure here.