Tailpiece
You can unlock a Jackdaw-specific look for everything but the Shields category, and luckily, the challenges to do so aren’t too difficult at all.
Not so lucky is the fact that these are only available for a limited time and will go away on February 25. Be sure to complete these challenges before time runs out.
How to view challenges
The first thing to note is that the game doesn’t tell you about the challenges you need to complete in order to unlock the Jackdaw cosmetics. The challenges are through the Ubisoft Connect service, which you can access by going to the Main Menu and selecting the option for it.