Prepare apples and syrup: Melt 6 tbsp. butter in a 12-in. nonstick frying pan over medium heat. Add honey, 2 tsp. lemon juice, 1/4 tsp. cinnamon, and apples. Cook, stirring occasionally, until apples are lightly glazed and have softened slightly, about 10 minutes.
Meanwhile, in a medium saucepan, whisk together 3/4 tsp. cinnamon, the sugar, and cornstarch. Add apple cider and 5 tsp. lemon juice and whisk to combine. Bring to a boil over medium heat and cook, stirring often, 2 minutes. Remove from heat and whisk in 3 tbsp. butter.
Make waffles: In a medium bowl, whisk together flour, baking powder, baking soda, salt, sugar, ginger, nutmeg, and cinnamon. In another medium bowl, whisk egg yolks until pale yellow; whisk in oil, buttermilk, and pumpkin.
In bowl of a stand mixer fitted with the balloon whisk, beat egg whites until soft peaks form. Add egg yolk mixture to flour mixture, stirring to combine. Gently fold in egg whites just until blended.
Preheat oven to 200°. Preheat a waffle iron and coat it with cooking-oil spray. Ladle 1 cup batter (or amount directed by waffle-iron maker) onto hot iron, spreading with a spatula, and cook until nicely browned, about 5 minutes. Transfer waffle directly to oven rack. Repeat with remaining batter. Meanwhile, reheat apples and syrup.
Break waffles into sections, divide among 8 plates, and top with apples and syrup. Serve remaining syrup on the side.
Note: Nutritional analysis is per 2 waffles with 1/4 cup syrup.