Think I also read that the iPP doesn't support Portrait mode on the rear camera (but still does on the front TrueDepth camera). That would be odd, as the iPhone 11 with the same wide/ultra-wide combination does. (Plus, you would expect the inclusion of the LiDAR sensor to help in creating far more accurate depth maps.)
I wouldn't be surprised if Apple wanted the iPhone 12 (presumably with LiDAR) to get Portrait mode improvements first, and it to be added to the iPad in iOS 14.