Bring a large pot of water to a boil over high heat. Season the water generously with salt. Add the Sardinian Gnocchi and cook until the pasta is floating and barely al dente, about 2 minutes. Reserve 1/2 cup pasta water, then drain well.
Meanwhile, heat a large skillet over medium-high heat. Add the oil and garlic and cook until the garlic is fragrant, about 2 minutes. Add the shrimp, pepper flakes and 1/2 teaspoon salt. Cook, stirring often, until the shrimp is pink and almost completely opaque, about 1 minute. Deglaze with the wine and season with 1/2 teaspoon salt. Simmer for 2 minutes to reduce slightly and finish cooking the shrimp.
Add the pasta to the shrimp mixture and sprinkle the bare pasta with the Parmesan. Top with the arugula and lemon zest and toss well to combine, adding pasta water if needed to maintain a sauce, until the arugula is wilted. Serve topped with additional Parmesan if desired.
In a large bowl, combine the semolina and 00 flours and form a well. Add the water and salt to the center of the well. Using a fork, slowly start to incorporate the flour into the water to form a rough dough. Add a teaspoon of water if the dough is too dry or a dusting of flour if it is too wet.
Lightly flour a smooth work surface and pour the dough onto the flour. Knead the dough until it springs back when you press a finger into it, 8 to 10 minutes. Flatten the dough into an even square. Wrap the dough well in plastic wrap and allow to rest for 1 hour.
Cut the dough into 6 pieces. Roll a piece into a 1/3-inch-thick rope. Cut the rope into 1/3-inch pieces. Press one piece of dough firmly with your thumb against a gnocchi board or the back tines of a fork, rolling the dough as you pull it along to create a shell shape. Continue with the remaining dough, dusting the pasta with 00 flour as needed to prevent sticking.