In a medium bowl, stir together onion, carrot, pickles, lemon juice, sugar, and ½ teaspoon salt. Set aside.
In the meantime, in a medium pot over medium heat, combine macaroni, 2 cups water, and remaining ½ teaspoon salt and bring to a boil. Cook, stirring frequently, until pasta is al dente, about 5 minutes. Drain immediately and let cool slightly.
In a large bowl, stir together tuna, mayo, paprika, and pepper. Fold in pasta and pickle mixture until well combined, then top with eggs.
Garnish with scallion before serving.
