Start Oculus Unity app from standard Android app

[theblitz1959]

We have a standard Android app which gives the user the option to switch to VR.

The VR is a separate Oculus Unity build app.
What is the best way to start the VR app from the Android app?

Should it be done via and Intent - in which case what Intent should be used - or should it be done via a Broadcast?

There are other questions about this but they seem to be old and aren't clear.