The issue seems to be something like the following...
When starting from a new pyui file, if you add a navigation view and then add views within the nav view using the UI designer, those views do not appear as .subviews. Where are they? I think that this is essentially an attempt at creating a root view of the nav controller. Also an issue with this approach is that any subsequent views pushed to the stack will underlay the buttons and touch event on the pushed view will not work.
One solution could be to instead programmatically push another pyui file with your buttons onto the nav stack. However, this results in odd behavior because the view pushed will seem to be the second view on the stack. I.e. You will be able to navigate backwards to an empty view from the button view.
I can't seem to find any relevant example code.
I'm also unsure how to use the NavigationView in this way. I've placed a tableview within the nav and I'm unsure how to access this root view in code to set the delegate and data source so that I can push selected table rows onto the stack. I know that I can call push and pop once I have an initial selection, however.