PI zeros are made by the foundation and are shipped to pimoroni , pihut , adafruit and micro centers US
there are threads hear about that but I dont have a link ATM [the website is very slow for some reason
I think its very cool that rpi foundation are supporting small electronics development/retail companies.
I think all those suppiers also develop and produce add on boards for the rpi and the pizero deal helps them get their other stuff out to the public and enlarge their direct sales by sending web traffic to their sites.
Maybe the foundation should offer something similar to other hackers/developers that can show they have a reasonably educational focused rpi 'add on'.
Maybe allow selling through the pi swag store, or allow batch ordering of pizeros if the 'add on' creator can prove they are not going to scalp them on ebay?