In a large bowl, combine the ground pork, ground beef, breadcrumbs, parmesan cheese, egg, garlic, salt, and pepper. Mix gently with your hands until just combined. Roll the mixture into small meatballs, about 1 inch each. You should get around 30 meatballs.
Set the Instant Pot to saute mode and add the olive oil. Add the diced onion, carrots, and celery. Cook for 4 minutes, stirring occasionally, until the vegetables begin to soften. Add the garlic and stir for 30 seconds.
Pour in the chicken broth and stir in the italian seasoning. Scrape up any bits from the bottom of the pot. Gently drop the meatballs into the broth one at a time.
Add the pasta and gently push it below the surface of the broth. Press cancel. Lock the lid, set the valve to sealing, and cook on high pressure for 5 minutes.
When the cook time is done, do a quick release by carefully turning the valve to venting. Open the lid and stir in the baby spinach. Let it sit for 2 minutes until the spinach wilts completely.
Taste and season with salt and pepper as needed. Ladle the soup into bowls and top with freshly grated parmesan cheese.