You can listen to all of our live and on-demand content on HomePod by using AirPlay from the BBC Sounds app on your iPad, iPhone or iPod Touch.
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