Preheat oven to 400 degrees F. Line a baking sheet with foil; grease foil. Set baking sheet aside. Unroll pizza dough onto a lightly floured surface. Roll dough into a 15-inch square. Cut dough into nine 5-inch squares.
For filling, combine bison pepperoni, mozzarella cheese, the 1/2 cup pizza sauce, and the green onions in a medium bowl. Place about 3 tablespoons of the filling on each dough square. Fold one corner of each square over filling to the opposite corner, stretching dough as needed to cover the filling. Seal edges and prick tops with a fork.
Place turnovers on the prepared baking sheet. Brush lightly with milk and sprinkle with Parmesan cheese. Bake for 15 to 18 minutes or until golden brown. Serve with additional warm pizza sauce.