After coming up empty on his search for a device that would simply let him plug in a Pi to a wall outlet and have it display useful information, Jamie Bailey got to work creating such a unit himself. What he designed employs a Raspberry Pi Zero W and a 2.23” OLED Bonnet from Adafruit to show temperature and humidity data, mounted to the top of a USB wall charger with an adapter.
He’s using all off-the-shelf parts here, and with the Pi Zero WH version there’s not even any soldering involved. The one trick is that the USB to micro USB adapter may make such a setup face the wall, a situation that he encountered and was able to remedy with a USB-C port and another adapter.
The screen is programmed to switch between his crawl space temperature/humidity (obtained with another Pi Zero W as outlined here), along with attic and outside temp/humidity numbers. It also displays the IP address of the device, which would be quite helpful when changes are needed.
Code for the project is available in Bailey's article. While fairly straightforward hardware-wise, the idea that you can plug such a device wherever there is an outlet and WiFi could be handy in a variety of situations!