Currently dashboards are centered around displaying device data. Data Tables are a brand new additional to our platform and we’re still investigating the best ways to expose the ability to display data from those.
An interesting work-around for now could be to record the delta onto device state. You can setup a timer to trigger once an hour. The workflow could then retrieve the most recent two entries from the data table, calculate the delta, and record it on a device’s state. Once the value is on a device state, you can display it using any number of dashboard blocks.