Vocoding white noise with speech sounds like hoarse whispering, it’s still identifiable … Making yourself sound like an old man - #2 by Trebor . Any voice manipulation you can do in Audacity is reversible.
Speech to Speech AI is the best option … https://youtu.be/0UVppC0Ihjk?&t=70
but some people can be recognised by their speech patterns & vocabulary even if someone else is reading their words.