The Windows 10 Store app was recently updated to v11602.1.26.0
This new version bring the support of HoloLens screenshots.
As you know, when you are viewing a UWP app, you can select to see either PC or Mobile screenshots.
With this new update, if an app is available on the HoloLens, you can now see HoloLens screenshots of the app.
Take for instance, the "Get Skype" app which apparently is also available for HoloLens...
This is a good way to know if an app is available on the HoloLens.
I cannot confirm if this new feature came with this latest update, but that's what I noticed.
It would be nice to see Xbox One screenshots (the Xbox One will soon be able to run UWP apps), Or even Microsoft Band 3 screenshots, if ever Microsoft figure out a way to make the wearable run on Win10.