- (Answering in English for everyone's benefit, I hope that's OK).
For each Nexus device, both Google and the device manufacturer get closely involved in all phases of development (including testing), along with the relevant silicon vendors and operators who each bring their own expertise.
At the technical level, generally speaking there are different mechanisms used in the Android ecosystem to deploy updates to user devices. Google has its OTA mechanism, which is used for all Nexus devices (as well as some other devices). That means that at the technical level the OTA is sent from Google servers. That's just the technical aspect, though.
When it comes to approvals, it becomes hard to speak in general. Lots of companies have some input, and the process for the final approval and the OTA schedule depends on many factors, which vary per manufacturer, per device, per country and per operator.
Because there are very many combinations, and because my job is somewhat remote from those concerns, I'm not in a position to provide with certainty all the details that could be relevant to a single device (in your case, sojua at Rogers). At the level of my job and in the context of this post, I know that there've been enough approvals to allow me to distribute 4.0.4 factory images for soju and yakju, but not yet for the other variants.