Preheat the oven to 400 degrees. Cook the sausage in the oven until nicely browned to an internal temperature of 155 degrees using a thermometer.
Make the topping: Heat butter over medium-high heat in a skillet. Add apple; cook for 3-4 minutes or until tender. Stir in brown sugar, maple syrup, and cinnamon; cook and stir 1 minute longer. Remove from heat; cover with a lid to keep warm.
Make the pancakes: In a large bowl, whisk flour, sugar, baking powder, pie spice, and salt. In another bowl, whisk eggs, milk, and pumpkin until blended. Add to flour mixture; stir just until moistened (keep lumpy; do not over-mix). Fold in walnuts.
Lightly grease a skillet with nonstick spray; heat over medium heat. Pour batter by 1/3 cupful onto the skillet. Cook until bubbles on top begin to pop and the bottoms are golden brown. Turn; cook until the second side is golden brown.
Top the pancakes with apple topping; serve with sausage and orange juice.