navigation controller modal dismiss via custom transition

Hello everyone,

I am working on a project where I am in need to present modally a view controller embedded inside a navigation controller, since the appearing view controller is the first VC of a specific application flow.

The issue that I need to solve is the drag-down-to-dismiss interaction, which would be "easy" to tackle since via transitionDelegate it is simple to find help online, but I am trying to dismiss interactively - the dismissal has to follow the finger panning on the screen - a NAVIGATION CONTROLLER, and reading documentation and forums on the topic, navigationController.delegate only handles custom interaction and animations for push and pop events. Dismissal is never mentioned. Thanks for any suggestions.