I managed to create a gamepad-like control method and used Box Colliders to trigger actions ( Unity TIp: Creating a RealSense-Powered Menu In Unity ) just like your example. I was able to simulate keyboard arrows and trigger movement of the player based on the collider.
May I know if it is possible to control a bluetooth robot, which uses arduino, based on the controls triggered in Unity?
If you search YouTube for 'unity robot bluetooth arduino' then you can find some videos that demonstrate controlling an Arduino robot through Bluetooth via a Unity app. I do not know how you would actually build that though.
Since you can use RealSense to input values into Unity joypad control axes, I would speculate that you could indeed use RealSense with a Unity app to control an Arduino robot by Bluetooth.
This video has an Arduino to Unity tutorial.