It certainly is cool – and we have a lot of things planned that are going to take it to next level – like dynamic content
WordPress is still working on the Navigation Block. It’s available as an Experimental option in the Gutenberg plugin – their planning it for the next editor update. Which i hope is soon as its the missing element today.
You can merge a Block Element with the Site Header / Navigation.
Just create a new header element – don’t add any content – go to the Site Header tab and merge with content.