Hello, I would like to share my experience on getting my passport back after I received PR approval.
If your passport was seized in the Etobicoke office. You have to write a letter requesting the passport with your information and take the letter to the Canada Border Service office, address: 6900 airport road, Mississauga, ON. They will contact you in 2 days to give you the passport at the same office. I did all this in-person over a month ago. It was very easy.
This office is where they keep all the seized passports.