@bravenel I realize I started this topic back in June making nearly this same request. Your response then was that there was no mechanism in the hub to pass those times to apps, which I accepted, as the "Zigbee Details" page format led itself to a very easy screen scrape to get the info I wanted for all available devices.
Sadly, the 2.3.7 update to that page broke that, rather completely.
So, this second request: a mechanism to access the Last Message info, as it's shown on the "/hub/zigbeeInfo" screen. Best for me (and perhaps for you) would be an URL (like "/hub/zigbeeInfo/LastMessage") that would list the device IDs and "Last Message" time strings for all the devices on that screen, comma-separated, like the display for "/hub/advanced/freeOSMemoryHistory".
I'll understand if the answer's still "no", but you can't blame a guy for asking.