Preheat oven to 350 degrees F (175 degrees C). Place duck on a baking sheet. Bake in the preheated oven until heated through, about 7 minutes. Mix curly endive, arugula, radicchio, grapes, apple, turnip, and pecans in a large bowl. Whisk olive oil, maple syrup, vinegar, salt, and pepper together in a bowl; pour over salad and toss to coat. Divide salad between 2 serving bowls and top each with duck confit.