Based on the feedback from GS PX Support, there is currently no way to see where Segments are being used.
Having visibility on this would help, among others, to:
- Clean up data
- Revise current Engagements
- Take an informed decision on whether to remove/update a segment
As a reference, you can see what is happening with GS NXT and the Templates. I can see in how many Programs they are being used:

And also the details of the Programs, when I select the number:

Thank you!