Make Audio Element Persistent Across Pages

Maybe the “normal” wordpress themes are not the right tool here, and what you need is a “headless” wordpress with {insert JS framework} to get the content via the json API and handle the page routing without performing actuall page refresh.

Another possible solution is to turn it from audio to video as browsers now have the capability to detach a video out of the browser window which means they should not be impacted by browser navigation