-“I am one of the few who have a Weatherunderground API key that actually works”
As we described in this support article:
https://openthings.freshdesk.com/support/solutions/articles/5000017485
currently there is still a way to obtain a WU key even if you don’t own a physical PWS device.
-“device ID section”
This doesn’t matter, you can ignore it. This is for OS 2.x.
-Please note that to use WU PWS, you must select a PWS. To do so, go to Edit Options->System and click on Location, it should show you PWS stations near you in blue dots. You need to select one of them. If you don’t select a PWS (blue dot), it will still use DarkSky. This is because WU API only works if the location is in the form of a PWS name. GPS coord does not work with WU API.