A while back i created picture cards of the playlist. then used action to trigger the service to select the source. i’ve changed setup since, but have a look at https://github.com/kalkih/mini-media-player
Then check the source list, and you should be able to trigger that (from memory source list was a radio station, TV, and then a bunch of my playlists from spotify)
not complete info but HTH!
There isn’t a full solution for perfect harmony with hass/sonos/spotify. You can only use Sonos to call Spotify. Mark your playlist as a favorite in Sonos app, then play the favorite. I don’t believe you can play specific songs. This works for anything, not just spotify.