So it is now globally available via the Office App store. If you use Excel 2016 or Excel Online, you can install and try out the app.
Below are the installation steps for Excel 2016.
And if you use Excel online:
Upon successful installation, you will find the add-in under the Home menu as the last item on the right.
It is the first version and I plan to radically improve its design and add to the functionality. You can help shape future updates by installing it, using it and letting me know your feedback.