Italian Wedding Soup

In a large bowl, stir ground chicken, chicken sausage, bread crumbs, Parmesan, oregano, garlic, and egg until combined. Season with salt, pepper, and red pepper flakes if using. Form into meatballs approximately 1" in diameter to make about 22 meatballs. In a large Dutch oven or stock pot over medium heat, heat 1 tablespoon oil. Cook meatballs in batches, until outsides are golden and insides are cooked through. Remove from pot. Heat remaining oil then add onion, carrots, celery, and thyme. Cook until fragrant and starting to soften, 3 to 4 minutes. Add chicken broth and bring to a boil. Add pasta and meatballs and lower to a simmer. Simmer until pasta is cooked, 5 to 7 minutes. Stir in spinach and cook until wilted, about 1 minute more. Garnish each bowl with dill and more Parmesan, and serve with a lemon wedge.