When you create a chart on a feature class in Pro, there are many customizations that can be set up. You can label the axes, format the numbers, add guides, change the colors, and so forth to ensure that your chart is easy to read. No such options are available in the pop-up charts, but if they were, it would make the pop-up charts far more useful. As-is, there is so little customization available that most charts are largely useless.
