What I can’t figure out is how to swap out the data table and get it to update a plot instead. I can get the scatterplot to show, but not update.
You should be able to do this by linking the glyphs in your plot to the column data source you update on callback. There are a few examples of this towards the bottom of this page and some more info and examples here.
Also, If you are able to share a reproducible example that illustrates where you are getting stuck, there is a good chance that someone on the mailing list can help you figure it out.