Place large pot on stovetop over medium-high heat. Add 3 tablespoons avocado oil to pot and heat oil until hot and shimmery.
When oil is hot, add 1 pound ground chicken to pot. Cook chicken 3 minutes, stirring occasionally until meat begins to break into small pieces.
When ground chicken begins to crumble, add ½ teaspoon garlic powder, ½ teaspoon salt, and ¼ teaspoon freshly cracked black pepper to pot and stir to incorporate. Cook chicken, stirring frequently, approximately 2 minutes or until meat is cooked through.
Using slotted spoon to drain liquid, transfer ground chicken to small bowl, packing chicken into bowl tightly to retain moisture. Cover bowl with lid or kitchen towel and set aside.
Add 1 tablespoon avocado oil to pot. Heat oil over medium-high heat until warm, then add 2 tablespoons minced garlic, 3 large stalks celery, 2 medium carrots, 1 cup chopped white onion, 1 teaspoon salt, and ¼ teaspoon freshly cracked black pepper.
Stir ingredients together and cook, stirring frequently, approximately 5 minutes or until onion is translucent.
When onion is translucent, add 7 cups chicken stock to pot. Stir to incorporate, then increase heat under pot to high. Bring chicken stock to rolling boil.
When stock begins to boil, add 4 ounces small pasta and reduce heat under pot to medium-high. Boil pasta 1 to 2 minutes less than time indicated on package instructions. Note: If pasta absorbs too much liquid, add ½ to 1 cup additional chicken stock to taste.
When pasta is al dente, return ground chicken to pot, along with any juices that accumulated in bowl while meat rested.
Cook ground chicken in soup 2 to 3 minutes or until chicken is heated through, stirring soup frequently.
Once chicken is heated through, add 1 teaspoon lemon zest and 1 tablespoon fresh lemon juice to pot. Stir to incorporate, then taste soup and adjust salt and/or pepper if desired.
Ladle ground chicken soup into serving bowls. Garnish with ½ cup minced fresh parsley divided evenly between bowls and serve immediately.