Heat olive oil in a Dutch oven over medium heat until shimmering. Add pancetta and cook until rendered, 3 to 5 minutes. Stir in onion and celery, cooking until softened, about 5 minutes. Add garlic, oregano, red pepper flakes, and anchovies, stirring until fragrant, about 30 seconds.
Stir in chicken broth and water, scraping up browned bits. Add diced tomatoes with their juice, cannellini beans, Parmesan rind, and salt. Bring to a simmer and cook until flavors meld, about 10 minutes.
Increase heat to medium-high and bring to a boil. Add orzo (or preferred pasta) and cook until al dente, about 8 minutes. Discard Parmesan rind.
Stir in parsley and adjust seasoning with salt and pepper. Ladle into bowls, drizzle with olive oil, and sprinkle with grated Parmesan.