How can I make the Audio Visualizer listen only to one app?

I want to have the Audio Visualizer react ONLY to Spotify, and not to the entire audio of my PC (i.e. Discord, a game I am playing, etc.); is this even possible? I have tried setting the Visualizer to work on my virtual cable, but that would require me to have Spotify also on that output, and I can't listen to that and my default playback both at the same time. I've spent hours trying to figure this out and I give up.