BTW Both Pandora and Spotify play nice with Apple Music, but not Sonos

This is as expected. Apple have no idea what Sonos is playing unless you use AirPlay, which is #1 in your list, and #2 is not.

I don’t understand your second post: how does Pandora play nice with Apple Music??

I can change song within Pandora and Spotify, the new song plays & also appears in iPhone Control Center & shows as playing in Sonos App. 

If I change song within Sonos App, new song plays .. AND the new song appears in Pandora and Spotify. 
 

So, if I have this straight, Apple Music, Pandora, Spotify definitely all support Airplay from my iPhone to the Sonos speakers. I can change songs within each of these apps and the new song appears in the iPhone’s Control Center. 
 

But your own Sonos App doesn’t because if I change songs within the Sonos app, the old song remains in the iPhone’s Control Center. 
 

Why does the Sonos App insist on being different??

 I am not trying to be mean here .. just trying to learn.

I have just the Sonos Ones right now .. am waiting for the Arc + sub-woofer  So my pair of Ones is currently set up as a Stereo Pair. Will delete Stereo Pair and reset as Surrounds when Arc comes  

The Apple Music, Pandora, Spotify apps are music players. They emit actual audio data, which is routed through the audio system on your iPhone, which is in turn hooked up to the control center, and those apps also provide the metadata for track/artist etc.

The Sonos app is not a music player, it is a remote control. It sends no audio, anywhere, though many think it does.

However, both Pandora and Spotify have done work so those music services do communicate with the Sonos cloud system so they can keep “in step” when tracks change etc. Apple have chosen to not do this work for their SMAPI service.