Ask HN: Cross platform method for accessing system audio output?

I was hoping to create a desktop app that analyses the system audio output in real time. Eg. I can analyse audio coming from YouTube, or Spotify, or iTunes. Nothing nefarious, just visualisation.

I looked into Electron’s desktop capture, and it doesn’t work for mac. I also looked at Swift MacOS app, but I don’t think that’s possible without a seperate program called SoundFlower and I don’t think it can be packaged with the macOS app itself.

How might I go about creating a desktop app which can access the audio output feed of the host system?