Thanks, I am in! Only a few things: column colours are very visible and useful for Kanban, the + could be smaller and a side the title.
A Kanban implementation, plugin or not, would make Joplin a double super app! 
Now I am copying text from Joplin to a Kanban app and back, not a nice workflow.
But then it would have to be in the mobile version also, to become a complete home, travel and work note taking/planning environment.
Such plugin has to be coded in which code environment?