What current speaker(s) compatible with play:1, play:3 and Playbar

No current speakers are compatible with S1.  If you upgraded to S2, all current speakers can be in the same system as the units you have, meaning they can be grouped together.  No current speakers can be used as surrounds with a Playbar.

Thanks - I downloaded the new Sonos app today and ran through the process. Thought I was on to a winner but at the end the message “ this system is only compatible with Sonos  S1 controller. It isn’t compatible with your Sonos app”.

if all current speakers are compatible with Sonos 2 app why did the process to join fail?

All your listed units are S2 compatible.  I've no idea why the upgrade failed.  You may try calling Sonos support.

All of the products you listed are compatible with S2. Sonos app version compatibility

Check out this page:  Update to the latest Sonos app using the S1 Controller

At the bottom it mentions what to do if you already downloaded the S2 app and you get the not compatible message.

There are only two apps built by Sonos in the IOS Apple Store. Sonos S1 and Sonos. There is not one called Sonos S2 but assume the Sonos app is the S2 app and I’ve downloaded the wrong one?

The S2 app is named just Sonos, while the S1 app was renamed “Sonos S1” some time ago. Those are the only Sonos apps.

The Sonos app you see in the App Store is the same as S2. 

FWIW (not a bunch), I’ve run all products you listed under S2. I’ve since gotten rid of the PLAYBARs, but still am using the PLAY:1s and PLAaY:3s under S2. 

I shall try this tomorrow - I’ve followed the steps to the point where I got a your system is campatible for S2 but didn’t want to go further as were all watching TV and listening via Sonos 

If you are using a local music library, you should be aware that S2 uses (and requires) newer versions of the SMB protocol used for file sharing. S2 requires SMB v2 or v3 where the S1 system used v1.

What is an SMB protocol? I use iTunes for music- stored on a windows 11 laptop. I have iTunes playlists on my iPhone. Currently use Sonos S1 app on both the laptop and the iPhone to control the Sonos speakers / volume / etc. Where do I need to change the SMB protocol?

SMB is a method by which computers talk to data structures, like an NAS. I’m simplifying somewhat, read the link. 

Dou you use a Sonos Bridge in your set up? You do not mention it, but the Bridge is not S2 capable.

I don’t use a bridge - only the speakers listed 

OK. Then ​@jgatie ’s advice stands: time to call Sonos.