I agree that leaving out the critical import Observation was a huge oversight. I spent at least 20-30 minutes trying to figure out what I was missing.

Well, it is slight comfort to know that it works well on iPad. I had the same problem, too. I was not content to just play with weather kit—I made a menubar app—moving to iPad wouldn't work so well for that. I could change some code and move stuff around, but, no, I want it to work on macOS. I feel slightly better in knowing that it isn't just me—misery loves company? However, I kept reading and noticed I was getting errors about the sandbox and networking. Your log shows them too: PlayWithWeatherKit[16282:277991] [] nw_resolver_can_use_dns_xpc_block_invoke Sandbox does not allow access to com.apple.dnssd.service TL;DR I am now getting data. Yippee! I added both incoming and outgoing network options to the App Sandbox in Signing & Capabilities. The number of errors is reduced significantly and seems to be limited to the weather directory and bundle ID.