Quick TTS test, uses jslib to call js SpeechSynthesisUtterance.
sample project:
https://github.com/unitycoder/webgl-js-TTS
webgl demo:
https://unitycoder.com/upload/demos/webglTTSjs/
References:
https://docs.unity3d.com/Manual/webgl-interactingwithbrowserscripting.html