MQTT with a Pico Wireless pack

“This should be straightforward,” I thought, “I’ll just install umqtt.simple in the Thonny package manager.”

— turns out… that doesn’t work. I can sort-of get umqtt.simple installed by copying from micropython-lib into /lib/umqtt, but then it’s asking for usocket.

Has anyone managed to get a Pico with a Wireless pack talking over MQTT? Did you take notes? I’m at a bit of a loss to know where to start.