if you're visa-exempt for Canada, it doesn't matter. If you're non visa-exempt, then you need to have an authorisation to travel.
But assuming that you are from a visa-exempt, you can flagpole, and start the "waiting time". Then you can go to Europe, and travel on your EU passport. The problem for non-visa exempt applicants is that they need something to be let on a plane - to show that they are allowed to enter Canada. Airline staff are not trained to recognize COPR. but in your case, you can land, then go to Europe. To board the plane back to Canada, you just don't mention anything about being a PR. Just say that you're going for a visit. Then when you arrive in Canada, at the border you can show your COPR, or just let them know that you are a PR and they can check in the computer.
Good luck,
Sweden