It's basically a script that fetches the specified provider's API to get the sound file, and many other music services such as Spotify, Soundcloud, etc.
And then playing it in the page where the script is specified to play, for example, in a MediaWiki:Custom-BackgroundAudio:
Example|youtube|dQw4w9WgXcQ|5
It would play the audio from YouTube with the video ID of dQw4w9WgXcQ with a volume of 5 in the page "Example"
Is this possible? Or would it violate the customization policy?