Hello Joseph,
I understand you are not interested in a nice report that renders visually in Power BI which can be setup even to auto refresh and you (if you have Power BI pro user license as the sharing users) could shared with your other tenant users (even Power BI free) in your Power BI online experience... OK
You can still use Power BI free though
Open the Email Marketing Power BI report or create one for yourself with Power BI free.

The use the export functionality:

You can even choose yet another path - soon:
Today you can build a dynamic segment based on interactions of email open and identify all contacts who have opened a certain marketing message. And the upcoming UI enhancements in Segmentation will make it easier to do so.

Then you will be able to use "Export to Excel" in order to export the members and then can create an email based on the data.

Export will be supported later this year.