Most of it is processed on-device, and the Private Cloud code is open source (whether it's what they're actually using is another story).so the new 'apple intelligence' sounds rather insidious functionality -
Despite apple pleading for respecting security of your data, would you want all of you data emails/photos/searches/purchases/(calls?) 'crunched' by a LLM to allow it to subsequently help you,
like clippy the paperclip, your data also being potentially processed by 3rd party OpenAI
etc https://appleinsider.com/inside/apple-intelligence
You need to enable ChatGPT yourself, so it's exactly the same as anyone using it for anything, except there is some phone integration to make things easier.