There are definitely things under the google github org that are used in production, though they are typically mirrored from Google3 in some way. But not sure what, if any, has its origins in a personal open source projects.

i work on https://github.com/google/pytype which is largely developed internally and then pushed to github every few days. the github commits are associated with the team's personal github accounts. pytype is not an "official google product" insofar as the open source version is presented as is without official google support, but it is "production code" in the sense that it is very much used extensively within google.