The demo is using WebAssembly which is supported by Chrome. It also uses Web Audio API which I believe is again supported by Chrome. I just used the demo on my Android phone using Chrome. I wonder what could be a problem. It the mic on? :) If yes, maybe provide me the version of chrome you are using. I will look into it.

Works in Fennec (Firefox but from f-droid), but it took a sec to load the library it seems. Maybe that's the issue?

It works. But didn't on the first or second try for me. Suddenly it just worked. Dunno