You could either create a playlist of those songs, or simply ‘favourite’ them in the Apple Music App and then return to the service in the Sonos App and go to the playlist and hit the play/shuffle button.

This is dumb. When I open Apple music in Sonos and click songs there should be a shuffle button right there. Why do you have to make things so complicated???

The shuffle button disappeared when they updated the app. Sigh…

The playing queue ‘shuffle’ feature, will ‘likely’ be returning when Sonos get around to the queue management/editing in a couple of months (as announced), but there are shuffle options within the App on various playlists/albums etc. so perhaps just use those for now.

You can’t shuffle “songs” from your library in Apple Music using the app (you could with the old version). The only way to do this is use the desktop app; this then populates a playlist that can be viewed/played using the app on your phone/tablet. The shuffle button only appears in the new app for “albums”. 

I see shuffle available for both ‘albums’ and saved local library ‘playlists’ in the Sonos App, but I use .m3u playlists myself. See screenshot (example)