Heat 1 teaspoon of oil over medium-high heat in large skillet. Add sausages. Cook about 3 minutes or until browned, stirring occasionally. Transfer cooked sausages to a paper towel-lined plate to drain.
Reduce heat to medium. Add remaining 3 teaspoons of oil to skillet; add onion. Cook for 8 to 10 minutes or until tender and slightly caramelized, stirring occasionally.
Roll or pat dough into a 14-inch round pizza pan. Bake in preheated oven for 8 minutes.
Spread pie filling evenly onto hot crust. Top with cooked onion and sausages. Sprinkle with cheese. Bake about 10 to 15 minutes or until cheese is melted and crust is lightly golden. Top with arugula and serve.