Combine/mix another Web Audio audio context/stream to Jitsi IFrame API or Jitsi Meet Low Level API

Web project (see the sample project which can be modified to support another audio stream).

Project uses currently Jitsi IFrame API: https://jitsi.github.io/handbook/docs/dev-guide/dev-guide-iframe/
but can be changed to use lib-jitsi-meet (low level api) if needed.

Project has (audio.js) that generates demo noise sound to web audio context (audioCtx variable). This audio context is need to be mixed/added/combined to jitsi audio track/stream so that the remote participants can hear it too.

Some hints that might help:

1. Replace Jitsi Iframe API with lib-jitsi-meet and use SetEffect method
https://jitsi.github.io/handbook/docs/dev-guide/dev-guide-ljm-api

2. Modifying lib-jitsi-meet API to support second audio stream (not an input device)
API code has already AudioMixer class, could it be used?
https://github.com/jitsi/lib-jitsi-meet/blob/master/modules/webaudio/AudioMixer.js

3. Somehow to get it work with Iframe API
See for example these:
https://community.jitsi.org/t/use-multiple-audio-tracks-within-one-call/19573
https://github.com/p-fruck/jim/blob/master/index.html