Preheat the oven to 500°F. In a roasting pan, lightly coat the squash with oil and season with salt. Place in the oven and roast until the squash starts to color and is very tender, about 15 minutes. Remove the pan from the oven and when the squash has cooled enough to handle, peel.
In a medium saucepan over high heat, combine the squash, onions, and garlic, and onions and add enough water to cover the vegetables. Boil the soup until the water reduces to three-quarters of the original volume. Transfer to a blender or food processor and purée until very smooth. Season with salt.
In a small sauté pan over medium heat, warm the duck confit. When warmed, remove the leg from the pan, pull the meat from the bone, and shred it into small pieces. Place the shredded meat in a small bowl and season with salt, if needed.
In a small sauté pan over medium heat, toast the pumpkin seeds with the chili powder and ground coriander until the spices become fragrant.
Divide the soup into four warmed soup bowls. Top each bowl with the shredded duck and spiced pumpkin seeds. Drizzle the soup with the pumpkin seed oil and serve immediately.