In order to use this you'll need to do two things: Firstly enable Siri support for Kanbann on your *phone*, by saying "Hey Siri, Create a note Testing 321 in Kanbann" and tapping "Yes" (this is a one-time thing).
Create Trello cards using Siri on your watch: "Hey Siri, Create a note Testing 321 in Kanbann".
Secondly on your *watch* you need to designate the default list for new cards by navigating to a list, hard-pressing the screen, and tapping the "Set as default..." button.
Kanbann brings Trello to your Apple Watch.
Kanbann is in no way associated with Trello or Atlassian.
Use it offline or online, whether or not you have your phone nearby (it can work independently of your watch over Wifi or cellular).