Do you know if there is any way to show on the dashboard the last time the temperature was reported? I'm trying to display the "last update time" or "last activity time" that is held in the device details.
I think Last Update is most likely the last time the device was saved. Last Activity is what you are after, which unfortunately does no appear in the list for attributes when creating an attribute tile.
If you want it captured for a single device you may need to look at a virtual device and a rule, but let's wait to see if anyone else come's up with anything before going down that line. Your other option would be Device Watchdog which has an activity report, but that is more about monitoring of groups of devices more so that an individual device. Other than those, I'm not sure what access we may have to device events, they may be able to be used in some way as well... But I can't offer any experience there...