In the Red Christmas Truck Story, the red color of the truck is probably associated with Christmas. Red is a traditional color for the holiday, often seen in Santa's suit and Christmas decorations. So the red truck could be a symbol of the Christmas spirit. It may also be significant if it has a particular role in the community during Christmas, like being the vehicle that takes Santa Claus around in a local parade.
Kunlun was the center of the universe and the origin of the universe in ancient Chinese mythology. In ancient Chinese mythology, the Kunlun Mountains were regarded as the location of the North Star, which was also the North Pole of the world. The Kunlun Mountains held an important position in traditional Chinese culture. They were regarded as sacred existences and were often depicted as the heavens or the universe in myths.
The red truck in the story might hold significance as it could be the centerpiece of a community's Christmas celebration. Maybe it's the only truck in a small town that is large enough to carry the huge Christmas tree for the town square. It's not just a vehicle, but a part of the town's identity during Christmas time, with people gathering around it when it arrives with the tree, creating a sense of togetherness and holiday spirit.
I have no definite answer. Maybe it was inspired by real-life incidents, or maybe it was made up from scratch. More context is needed to figure it out.