Now you can just say "Hey Siri, Radio Channel ABC", and it will start playing. Works also with Airplay (Homepod etc).
You will need the stream address for the radio you want to listen to, and then you will need to add it to the app, and add a shortcut for it through the button in the app, and then you are all set.
This app can also be used just for playing streams, no need to use Siri if you are not friends with her.