Yes, with a Raspberry Pi, and sending data to the MQTT server directly with rtl_433 and the MQTT option.

But what’s all the GUI shenanigans for, then? There are so many configuration options under MQTT devices in the GUI, but nowhere to enter an actual MQTT topic. I wonder what it’s for.

I don’t think they will bother. They will end up in a landfill, and the school will buy new Windows computers.