How to create an ajax wordpress theme?

Question

WordPress

There was a need to create a Wordpress theme with an audio player in the header .. navbar .. without interruptions during transitions
Accordingly, by ajax, all content is loaded into the main div on click in the navigation (conditionally), and if everything is clear with the main page, then what about the rest? How can wordpress explain what to load when clicking on a link?
For example when going to mysite.domen/about WP should filter out /about and load the content in the main div
How is this implemented in WP?

Answer 1

REST API + frontend routing