Create an option to add an initial column to display additional information in Heatmap chart

What is the problem or goal the end user is trying to solve or accomplish?

Chart creators would like to add a starting value in the first column of a Heatmap chart. For example, the Subscriber column in the sample screenshot below:

What is the recommended solution by the Customer?

Create the option to add a standalone column as additional information for the Heatmap chart.