It could be quite easily patched to work with openHAB as a proxy.
I did some test a while ago during this PR.
I was able to play a radio stream through the audio servlet to a chromecast binding. Should be straightforward to do this on the WebAudioAudioSink by deleting the test and lines 74- > 83.
At the time, it didn’t seems a good idea. But maybe for the webaudio sink, it is ?