You'll need to grab a copy of this Siri Shortcut and then change the IP to the IP that runs MCWS on your network. It will ask you for an artist, then make a Smart Playlist called "SiriSmartlist" in Media Center. Then it will put a shuffle the list in Playing Now. Each time you use the shortcut, the contents of the Smartlist change... so it's basically a temporary container. Works on Apple Watch too.
Caveat:
If you invoke this shortcut by saying "Hey Siri, make me an artist playlist" then Siri will say "which artist?" Be warned that more obscure artists may not work. "Frank Sinatra" or "John Mayer" works fine, but "Jo Lawry" not so much. In those cases, press the shortcut to start it rather than using "Hey Siri" because then you can
type the name of the artist, in which case it works fine.
Link:
https://www.icloud.com/shortcuts/609cd3626385407d98ac6b238dc070d0