Run the shortcut. The shortcut will first ask if you want to search for the current song that's playing, or a specific song, or pick a random song from your phone's music library.
The first thing the shortcut does is determine what song you want to get a karaoke version of. You can choose a specific song, get the currently playing song if there is one, or pick 25 random songs from your phone's library and search for each of them.
If any results are found, you can preview or purchase the music right from within the shortcut. That's it!
The shortcut basically performs an algorithm I wrote to search the iTunes store.
First the shortcut asks the user what they want to use the search the iTunes store:
Then the shortcut collects two different search terms for the requested music:
Then the shortcut searches the iTunes store.
It removes any results that don't have the word "karaoke" in them somewhere to remove false positives.
Then it presents the results for the user to review.