Virtual Devices of many kinds are handy to use as “global” (Location or Account?) scoped storage.
ST could just give us more near-global variables at the account, location, or hub level, but we only get location.mode.
Virtual Devices are better, though as they fit in the security model, and events, etc…
Perhaps a Capability “Data” or some other capability name(s) would help make their purpose and use more obvious though.