I faced this challenge a couple places ago. It was a lot of information I had to dive into.
I started down this path.
https://support.avaya.com/support/en/products/P1706/avaya-equinox-vdi
But in the end. The Telecom team didnt like it, and they did this.
"The audio is offloaded but it does not go through the ICA virtual channel. The audio is encoded/decoded directly on the thin client and is sent/received directly between end points (peer to peer, Ex. thin client to thin client, thin client to physical desk phone….Etc). The agent controls the call through the Avaya App on the Citrix Virtual Desktop and the Avaya plugin/local app on the thin client mirrors the call control happening on the virtual desktop and sends the audio/media directly from the thin client hardware. I can demo this to anyone interested if it helps understand how this works."
The project got put on hold, and I never got a real world working setup. Only information. I wish I had more to share.