Our aim is to NOT introduce a proprietary customizer interface that may become obsolete as WP Full Site Editing evolves.
Today we have the foundations for building Headers in the Block Element.
The theme also has countless number of hooks which can all be accessed via the block element.
This covers the vast majority of use cases. eg. a Call to Action button in the nav.
Once the Nav Block is available users will be able to create the full header in the block editor.