The application I'm working on, I went with a 3-state navigation... null (default), true (open) or false (closed) ... at large screen sizes null is a soft open, smaller soft closed... toggling goes between the respective hard state and the null/default state. At sm-medium, it's an overlay, at phone/xs it takes over the screen.

I find that this is more intuative to use than a hard on/off only.