It could be a while before Spotify supports Siri Shortcuts. In the meantime it is easy to create your own, although with the disadvantage of you needing to unlock your phone.
Here is a shortcut I created to more quickly calm my crying daughter who responds well to white noise.
You can grab the URL for any Spotify track by tapping the button to the right of the track and selecting Share. You can then choose Copy Link. Just paste that into the URL Shortcut action and then open the URL.
I’ve assigned the Siri Shortcut “White Noise” to this. Much quicker and less frustration all round than lots of taps in Spotify.