The Calendar is usually in the right sidebar. Open the sidebar by expanding it (button at the green arrow) or Ctrl+P and typing “Toggle right sidebar”. If the calendar isn’t there, Ctrl+P and type “Calendar: Open view”.
Kanban is just a special type of note: You can right-click on a folder in the File Explorer and choose “New kanban board” or Ctrl+P and type “Kanban: create new board”.
The calendar works too!
But I was being stupid too!
I didn’t adjust the bar for Right sidebar. I play with it just now, and what do you know, it shows up!