On a PC, is there anyway to run visualizations with Pandora Radio. I realized Pandora itself does not have visualizations, but is there some way to rig it up with another piece of software?
You can use use Winamp's visualizations, by configuring Pandora's output to plug into line-in, it should work.
Detailed steps at Winamp forums
It's possible to create your own stand-alone visualizer that will work with either Pandora or Spotify. I have mine hooked to a 4K TV. This is a Mac approach, but can be done with Windows. https://mhd.tips/spotify-visualizer-medium