How can the controller state be read without the use of an HMD?

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If the controller has sensors or buttons, you can likely read its state without the use of an HMD. Many controllers have LEDs or other visual indicators that can provide information on the state of the controller, such as whether it is turned on or off, or whether it is connected to a device. Additionally, some controllers may have audio cues, such as beeps or chimes, that can indicate various states, such as low battery or successful pairing with a device. Lastly, if the controller has Bluetooth capabilities, you may be able to read its state through a smartphone or other Bluetooth-enabled device.