Your question has been answered multiple times in this thread and the answer appears to clearly be no. Apple will not allow an app to even mention that they can

Your question has been answered multiple times in this thread and the answer appears to clearly be no. Apple will not allow an app to even mention that they can get it at a cheaper price on another device. Personally, I think if Apple will continue to insist on this anti-competitive behavior, iOS users should just pay the 30% more for their subscriptions (so app developers end up with the same revenue) for the benefits you describe unless they're savvy enough to actively look for other payment options on desktop, Android, etc.