Would be great to be able to make a card which you can make global and therefore add to multiple dashboards you create. This would help people building their own snazzy full screen dashboards on tablets (example using IOS themes and mushroom cards).
You could then create a “global” navigation bar with something like mushroom chips have links to all different pages/dashboards - and even incorporate the new back button feature.
I know mushroom cards is a HACS custom frontend thingy but assuming that the Home Assistant core needs to have some base feature added before people can incorporate this into any card standard or custom (say a global toggle option on cards). Might be wrong so happy to be corrected.
Global cards would also help users create a card they could re-use in different dashboards with say different user restrictions. Hope that all makes sense and have to say love all your work on HA!