If you look at the OTA pages for Android, there are some specific Telus builds, although it looks like for Android 9 Pie there is no custom Telus build for the Pixel 2.
I have the Pixel 2, and received the OTA this afternoon.
All updates for Google devices come from Google! The same applies for almost all other devices as well, including LG, Huawei, and Samsung.
Edit: Just to add as to why you might not be able to download the update yet OTA. Updates go out in waves and it can sometimes take a couple of weeks and longer for a particular device to get an OTA.