Yes it is directly integrated. Having said that the integration is pretty limited in as far as controlling the speaker. Pretty much play and stop. You can’t command it to play a specific Pandora or Spotifiy station via Smartthings so you still have to use its Multiroom app. You can use the Sonos Smartapps to do text to speech. I use mine to announce that “Today is trash day” every Tuesday morning, Says goodbye when I run the goodbye routine plays the last Pandora station when the I’m back routine runs and plays an alarm sound at 100% volume when SHM is activated.
The only complaint I really have is occasionally, one of my three speakers will fall out of the group and not be recognized until I power cycle it. BTW smartthings will not play to grouped speakers, only a single one.