If you use the PoodLL or VideoEasy filters to handle the audio files, then you can specify alternative html tags to to display the media files on mobile. In this way you can centralise the display logic, so that you do not need to alter 15000 audio file embeds.
PoodLL and VideoEasy use user editable templates to make the players that handle the media. You might choose as a template "mediaelement audio" preset. That would use that player on browsers, but in the case of the Moodle mobile app it will instead deliver standard html5 audio tags. You can see these in the "alternate content" fields at the bottom of the template. If that works out of the box for you, that would be good. But you should be able to alter those template fields to get just the output what you want.
Some docs are here for Poodll,
https://poodll.com/poodll-3-docs/templates-and-bundles/
but the same applies to VideoEasy.