Hi
a few quick comments...
Generally audio is less of a concern because of the smaller file sizes involved compared with video, especially if the audio is encoded as mp3 and at appropriate bitrates etc for the purpose e.g. narration rather than music so relatively small file sizes.
The Xerte authoring interface where you add audio will accept URL links to .mp3 files but typically that isn’t going to be much different to uploading the mp3 directly.
Some third party audio streaming services may provide an embeddable player, or possibly even a direct mp3 link, but such services are usually aimed at music consumption and likely to be charged at a rate that isn’t viable for just ‘narration’ streaming. There may well be newer AI based applications that provide audio services with embeddable players or direct links but again I suspect would only be free for testing rather than production use.
In short the best thing with audio is to keep the file sizes as small as possible and use appropriate learning design to help with that e.g. granular separate clips rather than longer and therefore larger recordings.
Perhaps someone in the community will add further comments/suggestions.
HTH
Ron