Aside from the Pixel feature drop, Google is rolling out the next-generation Assistant that debuted on the Pixel 4 outside of the US. Canada will be one of the five countries getting the update. The others are Australia, Ireland, Singapore, and the UK. Google has started rolling it out on December 12. But these rollouts happen in stages, so if it hasn't made its way to your Pixel 4, just be a bit patient.
Unfortunately, the new Google Assistant will only be available on the Pixel 4, and it'll only support the English language for now. This next-gen Assistant introduces improved response speed by moving the language processing to the device. The update also brings a new look to Assistant.
Source: 9to5Google