BBC Sounds is not currently available via voice commands on Apple HomePod or Apple TV.
However, if you have the BBC Sounds app on an iPad, iPhone or iPod Touch, you can use the AirPlay feature to stream BBC Sounds to your Apple HomePod or Apple TV. This feature is not supported from an Android device.
Check the Apple Support website for advice on how to use AirPlay: How to AirPlay audio
BBC Sounds listeners on iOS mobile devices running iOS version 12.2 or higher can use Siri shortcuts to access BBC Sounds. You can create custom shortcuts to launch live radio via the Siri Shortcuts app.
More information on Siri Shortcuts can be found on the Apple Support website: Siri Shortcuts
