The thing is... Spotify doesn't seem to create an audio or video element to play these tracks so I can change the playback rate from the element reference, it creates an <iframe> element instead:
<iframe src="https://sdk.scdn.co/embedded/index.html" alt="Audio Playback Container" allow="encrypted-media; autoplay">
<html>
<head>
<meta charset="UTF-8">
<title>Spotify Embedded Player</title>
</head>
<body>
<script src="index.js"></script>
</body>
</html>
</iframe>
The script source is: https://sdk.scdn.co/embedded/index.js
Is the 'allow="encrypted-media"' telling me something?
I know this is possible on the official Spotify website, because a video or audio element is created, but since I'm using the Spotify Web Playback SDK, I can't do that.