In addition to the aforementioned recent breakthroughs for sound, there are definitely developments in and actors doing great work with music on the forum, too:
https://forum.makecode.com/t/at-the-speed-of-light/28169
https://forum.makecode.com/t/free-music/24638
https://forum.makecode.com/t/music/20722
https://forum.makecode.com/t/sound-effect-demo-no-extensions/5833
Probably much and many more. Maybe some of them would like to contribute?