How to assign function to the headset button ?

[focus3fan]

I would like to assign function (eg.  open menu, stop game and etc.) to the headset button. 
Do you provide an API for that? Please let me know if you have any sample code.

Environment

Device : VIVE focus 3
Engine : Unity 2021.3.7f1
Base Project : OpenXR for Mobile VR > Tutorial
Plug-in : VIVE Wave OpenXR Plugin - Android 1.0.2

Edited November 20, 2022 by focus3fan
add Tags