Thinly slice white and light green parts of scallions; set aside. Thinly slice dark green parts of scallions; set aside separately. Heat oil in a Dutch oven over medium-high. Add sausage; cook, stirring occasionally, until deep golden brown on both sides, 4 to 5 minutes total. Transfer to a small bowl; set aside. Do not wipe Dutch oven clean.

Melt 1 tablespoon of the butter in Dutch oven over medium-high. Add onion, celery, and bell pepper; cook, stirring occasionally, until softened, 4 to 5 minutes. Add garlic, Creole seasoning, and salt; cook, stirring constantly, until garlic is fragrant, about 1 minute. Add 1 tablespoon of the butter; cook, stirring constantly, until butter is melted. Add rice; cook, stirring constantly, 1 minute. Add tomatoes, stock, hot sauce, Worcestershire sauce, and reserved cooked sausage. Bring mixture to a boil over medium-high. Cover and reduce heat to medium-low; cook, undisturbed, 8 minutes. Uncover; stir mixture, scraping bottom of Dutch oven to make sure rice doesn't stick. Cover and cook, undisturbed, until almost completely tender, 11 to 12 minutes.

Uncover; stir in shrimp and white and light green parts of scallions. Stir to combine. Remove from heat. Let stand, covered, until rice is tender and shrimp are just cooked through, about 5 minutes.

Uncover Dutch oven; stir in lemon juice, 2 tablespoons of the parsley, and remaining 1 tablespoon butter. Divide evenly among 6 bowls; sprinkle evenly with dark green scallion parts and remaining 2 tablespoons parsley. Serve immediately.