Pro Raw is supported on iPhone 12 and later, so I would expect it on iPhone 15.
About Apple ProRAW
On iPhone 12 Pro and later Pro models with iOS 14.3 or later, you can take photos in Apple ProRAW. ProRAW gives you greater creative control when editing photos.support.apple.com
I agree with you. I misread the question. I think iPhone 15 Pro will support it, but the regular iPhone will not.Not a chance. There's no technical reason the base iPhones won't be able to do it but it's always going to be a Pro/Pro Max exclusive feature.
You can simply install an app like pro camera and shot raw images with every iPhone you choose. I even shot raw with my iPhone XR. Many 3rd Party camera apps are much more versatile in any case.Almost certainly not. It's a marketing feature for the Pro models.