I've spent the last week on this issue and it even rendered one iPhone 14 unrepairable. With the help of Apple Support, I figured it out today. First, you have to setup your new phone as a new phone, NOT by using your old phone. Once you go through the initial setup, you have to download iOS18. Only took about 45 minutes compared to the hours I waited thinking it was gonna load before. I sympathize with each of you that waited over night only to wake up to a still downloading phone. No bueno. After, iOS18 is downloaded, you have to go into settings and reset the phone. I reset all settings but kept the eSims. After the phone resets, you go through the initial setup again, but this time you can use your old phone to setup and transfer data. This data transfer was 30 minutes from the old phone, easy peasy. I did this twice and it worked, once on my wife's phone and once on my father-in-law's. I **** near cried after it worked the first time. Thanks to the Apple lady that helped me and I hope this helps you guys. Good luck.