downvote, it’s factually incorrect according to comments.
Agreed, but I’ll still give him an A for effort. The issue here is that any of these consumer grade power meters (USB or 3-prong) are all terribly inaccurate at low power draw.
The Raspberry Pi Zero seems similar to the ODROID W, a small low-power Pi clone with very low power draw. http://www.hardkernel.com/main/products/prdt_info.php?g_code=g140610189490