I've been using Unity 2019.4.11f1 and Google Cardboard 1.2.0 with no major issues. I've managed to integrate Vuforia 9.4.6 on Android, but not on iOS. If I have the Vuforia package, the cardboard VR will not start and otherwise, it will work normally.
So both Vuforia and Google Cardboard are vital to our app, and we need to find a way to make them work together on iOS. I figure it must be something specific, but I can't tell for sure.
The logs aren't very meaningful:
[Subsystems] Loading plugin cardboard_api for subsystem Display... [Subsystems] Failed to initialize subsystem Display [error: 1] [Subsystems] Loading plugin cardboard_api for subsystem Input... [Subsystems] Failed to initialize subsystem Input [error: 1]
Anyways, we have a thread on the official cardboard repository as well. I don't know which package is causing the issues.