Place pork, turkey, spinach, breadcrumbs, egg whites, oregano, 1 1/2 tsps salt & 1/2 tsp pepper in a large bowl.
With your hands, mix to combine. Roll into 1 - 1 1/2 inch meatballs. Arrange meatballs on a rimmed baking sheet. Lightly coat with cooking spray. Broil for 5 minutes. Turn meatballs and broil another 5 minutes, until golden brown.
In a large heavy pot, heat oil over medium. Add onion and garlic. Cook, stirring occasionally, until onion is translucent, about 6 minutes.
Add tomatoes and Sriracha and bring to a simmer.
Add meatballs and simmer at least 10 minutes. (To store, let cool, then refrigerate in an airtight container, up to 1 week, or freeze, up to 3 months).
In a large pot of boiling salted water, cook pasta according to package directions. Drain pasta, add to pot with meatballs and gently toss to coat.