You could check https://github.com/airander/A2DP-SINK. It is archived, but I hope at least the basic IOBluetooth implementation is still the same (or very similar).

The rejection is actually correct. They accept iOS 16, iPadOS 15.7, and universal apps at this time. If your app is targeting only iPad devices and you compile it with Xcode 14 (latest official release is 14.0.1), then your app is compiled with iPadOS 16 and it is not universal app, therefore it gets rejected. The solution (it is not a workaround, because there is actually nothing broken) is to download latest Xcode 13 version (13.4.1) and compile your iPad-only app. Apple's mistake, according to me, was to choose separate release dates for iOS and iPadOS. Because of this, they should provide an official way of compiling iOS 16 apps, but still reject pre-release iPadOS 16.

I am currently facing the same issue. We have a running intro price offer and an upcoming one. When I fetch the SKProduct and check the introductryPrice, it shows me the introductory price for the upcoming change and not the one that is currently active. Did you get any details why this happens or how to get the correct (currently active) introductory price?