Preheat the oven to 400 degrees F. Spread the sun-dried tomatoes over the pizza crust evenly, followed by the mozzarella and Gruyere cheese.
Heat the olive oil over medium heat in a large skillet. Add the bell pepper and saute, stirring frequently, until bell pepper begins to soften, about 1 to 2 minutes. Add the mushrooms and garlic and continue sauteing, stirring frequently, until mushrooms soften and begin to turn brown, about 2 to 3 minutes.
Scoot everything off to one side of the skillet and add the ground turkey Italian sausage. Cook, stirring occasionally, until sausage is cooked through, about 3 minutes.
Evenly spread the sauteed vegetables and sausage over the pizza (on top of the cheese). Place in the preheated oven and bake 10 minutes, or until cheese is melty and golden-brown.
Remove pizza from the oven and allow it to cool 5 minutes before slicing and serving.
*Replace Gruyere with more mozzarella if desired