OpenAI have some source code here -> https://github.com/openai/openai-realtime-embedded-sdk but not configured for the M5CoreS3
Oh and there is a new example that has dropped from espressif based on OpenAI's demo ->
https://github.com/espressif/esp-webrtc-solution/tree/main/solutions/openai_demo
Also not configured for M5CoreS3 out of the box.