"The StandaloneWindow module provides a way to create a separate window to display custom content. You are able to control a full-sized webview inside the window, therefore you can use HTML, CSS, and advanced techniques like WebGL to render the contents." [1]

So... someone could make a Webamp[2] plugin?

And Butterchurn[3] for viz? (Assuming one can plumb in a compatible audio node)

[1] https://docs.iina.io/interfaces/IINA.API.StandaloneWindow

[2] https://docs.webamp.org/docs/intro

[3] https://github.com/jberg/butterchurn

I was really hoping that butterchurn was a hi fidelity rendering of butter churning to the pacing and sound range of any given media that was playing