I'm not a lawyer, so I 100% would get official comfirmation but for my last PR card (2016/17) they held it "in process" a loooong time, so I had to leave Canada and I returned via Buffalo in a rental car with my original landing papers, my expired PR card, my original wedding certificate, copy of spouse's passport (they will be with you, so no issue there) and a complete copy of my PR application and the letter stating my PR card was waiting for pick-up. The agent looked quickly at my PR card and maybe my landing papers, smiled nicely, wished me a nice day... But again please, please, please call an immigration lawyer to confirm. My understand is you cannot be denied entry, but your status could be challenged by Imm Canada if you've not met some obligation. But that there is a process that would occur after you returned into Canada. But again, I beg folks not to take my word for it. Things can change and you don't want to be stuck because you listened to some schmuck on the internet.