Oh! Radio stations!
The one thing that I always wanted my HomePod to do was to be able to play radio stations without the need to stream via AirPlay from my MBP or iPhone.
I listen to Absolute Radio, and noticed this week that they have changed one of their jingles from "Ask your Google Hub or Alexa to play Absolute Radio" to "Ask your smart speaker" ... so I said "Hey Siri, play Absolute Radio" and guess what ... it did!!!
I also got it to play Capital and Heart radio, but not any of the BBC stations, nor talkSPORT or LBC. But it's a start .... :)