I once built a music game that basically ran entirely on SVG. We hacked Musescore to attach the same UUID to both the note head in SVG and the MusicXML object in two different output modes, and then used that to synchronise the sheet music scrolling with a MIDI stream. If you're interested you can see it in action in our failed Kickstarter video from like eight years ago: https://www.youtube.com/watch?v=vgbB5Q4-dgY