In a pressure cooker, combine 900 grams chicken giblets, 1 cup water, and 1/2 teaspoon salt. Cook for about 20 minutes.
Drain giblets and let them cool for about 10 minutes. Chop giblets in a food processor or by hand, then set aside.
In a saucepan, bring 2 cups uncooked white rice and 4 cups salted water to a boil over high heat.
Reduce heat to medium-low, cover, and simmer until the rice is tender and the liquid has been absorbed, about 20 to 25 minutes.
Spread cooked rice onto a baking sheet to cool for about 5 minutes, then transfer rice to a large bowl.
Mix in chopped giblets, 2 cups grated Parmesan cheese, 1/2 cup marinara sauce, 1/4 cup bread crumbs, 2 large eggs, 2 tablespoons chopped parsley, and ground salt and black pepper to taste.
Cover with plastic wrap and refrigerate for 1 hour.
Remove rice and giblet mixture from the refrigerator and form 2-inch football-shaped croquettes.
Roll croquettes in 1 cup bread crumbs and place on a baking sheet.
Heat vegetable oil in a large skillet over medium-high heat. Cook breaded croquettes until browned on all sides, about 10 minutes.
Transfer croquettes to a plate lined with paper towels to absorb excess oil.