I didn’t realise this until last night. You can use the Amazon Firestick with Voice view, without being tethered to a HDMI connection.

First, you must complete initial setup with the firestick connected through an HDMI receiver, such as a TV or audio receiver.

Next,

From the Home Screen navigate to settings.
Select ‘Controllers and Bluetooth Devices’,
Navigate to Other Bluetooth Devices’
Put your Bluetooth speaker in pairing mode.
Select your device from the ‘Discovered Devices’ list with the down arrow key and press select..

Once the speaker is paired you may disconnect the HDMI and use the Firestick wherever you have a solid wifi connection