Is it feasible to study for a doctorate in biology in the United States and find a job in Canada after graduation?

In fact, Canadians prefer to develop in the United States, but you want to come to Canada instead. If you are sure to immigrate to Canada or study in a local university in Canada, it will be easier to find a job, because the reality is that Canadians don't know much about American schools. Except for Harvard and Yale, there are only one or two local universities, so the competition is not very great.

Yes, if you find a formal job (and major-related), you can submit the immigration in about half a year, but the review time is very long, generally at least 1.5 years from application to approval.