Universal Device Poller data on Modern Dashboard

Hi, 

I've made some custom universal device pollers. I would like to publish some of the results as a KPI number on the modern dashboard.
I'm pretty sure that this should be possible with SWQL, but for some reason I'm not able to succeed. The universal device poller checks for the temperature on one device at the moment.

Can somebody provide a possible example on this? 

Thanks in advance,