This suddenly appeared in my environment (or perhaps it was always there lurking in the corner! It should also appear on your Windows 10 menu.
It’s a great way of finding out what is “new to you” in the Mixed Reality Environment:-
I hope that there will be options in the future so that you can target your specific interests and whether you are interested in 2d apps for pinning and playing within your environment or just “Full VR” Apps (or both) such that when you click on the bag you get a selection of new Apps that match those interests. Of course we are some way off that at the moment as far as full screen VR apps are concerned (unless Microsoft taps into the Steam menu?