Hi.
https://github.com/nordfalk/gvr-android-jme Is based on the more modern googlevr framework. I think it was mostly complete (at least up to the point of the last push) but had some issues with cameras or something.
I haven’t worked actively on this for quite a while, but my cardboard implementation (https://github.com/neph1/jme-cardboard) seems to be working also. I’ve pushed a few fixes in the last year based on user contributions.
I don’t know much about @oak1980 's implementation.
I suggest you start with GitHub - nordfalk/gvr-android-jme: JMonkeyEngine integration with Google VR SDK and fall back to the cardboard implementation if that doesn’t work as expected.
This thread contains the latest discussions: Google Cardboard support - #48 by Robinn