Sure but Microsof has the expertise and they own 49 percent of Open AI if I'm not mistaken. Open AI uses their expertise and access to hardware to create a GPT branded AI phone.
I can see your point re: run locally but no reason Open AI can't release version 0.1 and how many times are u left without an internet connection on ur current phone?
Overall I hate Apple now it's so stale compared to GPT's iPhone app. I nerd rage at dumbass Siri.