That isn’t entirely correct. I have been able to use Google VR on several devices now. The main thing is you have have to have Google VR services which are only on Android ‘N’ phone devices. Sadly, but understandable that a tablet like the Pixel C does not have the service. But the Nexus 6 and 6P do. However neither device will run the scanline racing feature properly, or at least in the UE4 version. Too much lag and double imaging as you move around. Also, I have not been able to get Vulkan to launch successfully either, it does work with ARM7, ARM64, OpenGL ES2 & ES3 + AEP. The four variant APKs are all contained in this zip package in a demo based on the 1st person project/VR template combination with a couple of other things thrown in. It is Gamepad and Cardboard Touch enabled to trigger the nerf ball gun. Simple but fun to launch all the primitives over the walls (in fact let me know if you project all the primitives over the wall). I have tried this on a number of phones ranging from a Note 4 to a Nexus 6P, as well as NVIDIA Tablet and Pixel C. Not all run in Google VR due to no Google VR service, but they will drop to Google Cardboard. So yes, UE4 now does Google Cardboard now 
Link to APK and OBB file. (NOTE: To reduce the file size of the APK you will have to copy the OBB yourself into the Android/OBB/xom.neodio.gvr_1st_person_HG64_nolatencyoff after you launch the app and get the error OBB missing)
Oh, and I am aware it should be “GVRFirstPerson” but I thought “GVRFistPerson” sounded strange enough I left is as is.