You can add the web UI page to your home screen.
Then, can you add new play/stop button or checkbox to stream audio only to the Web DVR UI?
https://IP:8089/devices/ANY/channels/XXX/hls?vcodec=none&acodec=mp3
I've recently discovered an easier method for live TV watching on my iPad via Channels DVR, a solution which specifically incorporates a Picture-in-Picture feature.
Rather than navigating Safari, or a bunch of bookmarks, which would require lots of navigation just to channel surf, I'm now using this app: https://www.tvstreamsapp.com/
I added the .m3u8 URLs for all of my favorite channels, which I got from the Channels Web UI.
The TV Streams app has versions for iOS, MacOS, and tvOS, and the bookmarks you add or edit sync across all platforms via iCloud. The basic version is free (ad-supported) and the Premium version is $8. Hopefully the developer of this app can easily add PiP when tvOS 14 is released.
Rather than hijack this thread I started a different one in the Hacks sub-forum.