Place an oven rack in the center of the oven, then preheat to 475°F.
In a large nonstick pan, add the Italian pork sausage. Cook, stirring frequently and breaking the meat apart with a spoon, 5 to 7 minutes, or until browned.
Add the tomatoes and chopped roasted peppers. Cook, stirring frequently, 1 to 2 minutes, or until the liquid is slightly thickened and the sausage is cooked through. Turn off the heat.
Cut the focaccia bread in half, then place on a sheet pan, cut side up.
Evenly top with the cooked sausage and sauce, mozzarella, and fontina.
Bake the pizza for 9 to 11 minutes, or until the edges are lightly browned and the cheese is melted.
Carefully transfer to a cutting board and let rest at least 2 minutes.
Cut the baked pizza into equal-sized pieces and enjoy!