You can cook a duck breast following the same instructions. Cook it until it reaches an internal temperature of 165 degrees using a meat thermometer. It will take about half of the time as a whole duck.
Using the slow cooker will result in soft skin, but tender juicy meat that falls off the bone. Getting crispy skin using this method can be a bit challenging due to the slow and moist cooking environment.
Once the duck has slow-cooked, you can transfer it to a sheet pan and then the oven on Broil for 5 minutes or for however long it takes for the skin to crisp.