Hi Calvin

Just saw your question and tried to do some research for you....

For everyday use, it works perfectly with Siri! Thanks to the new Siri button on the right side of the remote, you can find it pretty quickly now.

Unfortunately, I can't tell you for sure whether the initial setup also works exclusively via Siri.
Unfortunately, I read pretty much everywhere that a screen would be necessary for the setup...

- If another user is reading this: Could you try it out using only Siri?

----------------------------------------------------------------------------------------

Regarding the radio:

I quickly checked my Apple TV for you and can tell you the following:

On the one hand, Apple TV 4K comes with the Apple Music app. In it, you can listen to the various Apple radio stations, which are really very good.
In the App Store (in the Apple TV) I found various radio player apps, but also, for example, the official Energy Radio app, with which you can of course also listen to their own stations directly.

------------------------------------------------------------------------------------------

Regarding Airport Express:

Here I found an article from Reddit where a user asked exactly the same question. Another user confirmed that the connection was possible without any problems.
It may need a recent update on the Airport Express, but it seems to work.

Unfortunately, the only information I found on Sonos is that it doesn't seem to work with Sonos Port. However, the articles are a bit older, so maybe someone else here can confirm whether it works or not!
Via Airplay of course possible.

I hope that I was able to help you at least a little!

Kind regards