> Claimed that the existing training of the Sky voice was voiced by her?

That claim could very well be true. The letter requested information on how the voice was trained - OpenAI may not want that can of worms opened lest other celebrities start paying closer attention to the other voices.

They would create a voice in partnership with her? Not sure why you’re assuming it’s some insanely laborious process. It would obviously have been incredible marketing for them to actually get her on board.

Maybe they have second trained on her voice.

Voice cloning could be as simple as a few seconds of audio in the context window since GPT-4o is a speech to speech transformer. They wouldn't need to claim anything, just switch samples. They haven't launched the new voice mode yet, just demos.