Bloom the yeast by combining the warmed water, instant yeast, and sugar in a large bowl; let stand until foamy, 5 minutes.
Mix the dough: Add the bread flour and 2 tsp fine sea salt to the bowl and stir until a shaggy dough forms. Add 1 tbsp olive oil (for dough) and knead on a counter until smooth and elastic, 8–10 minutes.
First rise: Lightly oil a clean bowl with 1 tsp of the divided olive oil. Place the dough in the bowl, turn to coat, cover, and let rise in a warm spot until doubled, 60–90 minutes.
Make the sauce: In a medium bowl, stir together the canned crushed tomatoes, garlic, 1 tbsp of the divided olive oil, 1 tsp fine sea salt, and dried oregano. Taste and adjust salt if needed; set aside.
Cook the sausage: Heat a skillet over medium heat. Crumble in the Italian sausage and cook, stirring, until no pink remains and lightly browned, 6–8 minutes. Drain excess fat and let cool slightly.
Preheat the oven: Set a pizza stone or steel on the top-third rack and heat to 500°F (260°C) for 45–60 minutes.
Divide and rest: Turn the risen dough out, divide into 2 equal balls, cover, and rest 15 minutes to relax the gluten.
Shape and top the first pizza: Dust a peel or inverted baking sheet with 1 tbsp semolina flour. Stretch one dough ball into a 12-inch round with a 0.5-inch rim. Brush the rim lightly with about 1 tsp of the remaining divided olive oil. Spread about 1 cup sauce over the dough, leaving the rim bare. Distribute half the cooked sausage, then top with 8 ounces shredded mozzarella and 2 tbsp parmesan.
Bake the first pizza: Slide onto the stone/steel and bake until the crust is deep golden and the cheese is bubbling with some browned spots, 10–12 minutes. Transfer to a rack.
Repeat for the second pizza: Dust the peel with the remaining 1 tbsp semolina flour. Shape, brush the rim with about 1 tsp of the remaining divided olive oil, sauce, top, and bake as in Steps 8–9 with the remaining sausage, mozzarella, and parmesan.
Finish and serve: Let each pizza rest 2 minutes for the cheese to settle, slice, and serve hot.