In a large mixing bowl, combine softened cream cheese, pumpkin puree, graham cracker crumbs, powdered sugar, flour, and pumpkin pie spice. Mix thoroughly just until all components are evenly distributed—avoid excessive mixing. Cover and refrigerate for a minimum of 1 hour.
Once chilled, scoop out tablespoon-sized portions and roll them into compact spheres, roughly 1 to 2 inches in diameter. Arrange the formed balls on a wax paper-lined tray. Cover loosely and place in the freezer for 20 to 30 minutes to firm.
Meanwhile, in a heatproof bowl, combine white chocolate chips with coconut oil. Microwave in 30-second bursts, stirring after each interval, until the chocolate is fully melted and smooth.
Remove the chilled balls from the freezer and immerse each one into the melted chocolate, ensuring full coverage. Gently return the coated balls to the wax paper. If desired, sprinkle with additional crushed graham cracker crumbs while the coating is still wet.
Place the finished truffles in the refrigerator for about 1 hour to allow the outer shell to harden completely.