Unfortunately your replies are as unclear as Apple's.
You say they will work, but then say they wouldn't work. Seems very strange that noice cancellation and transparency work on Android and might not on older iPhones. However, I just don't know. Apple is not helping us on this one.
When my son returns with my Airpods Pro, I wil test them myself on a variety of iPhones and IOS levels. Apple, of course, would like us all to have the latest iOS version and newer devices, but they should be transparent about what the functionality is for ALL their customers.