I was working on a few Shortcuts which allow control of Spotify with the help of Siri and Shortcuts. It allows you to play the playlist you played last right from Siri e.g. you could ask Siri "Play Spotify" and the Shortcut will play whatever you last played in your Spotify account or to add the currently playing track to your Favorites and much more.
Have a look at the [reddit thread](https://www.reddit.com/r/shortcuts/comments/9h5aj6/control_spotify_with_siri/) for a complete list of features and an indepth explenation on how to set everything up.