We are happy to finish the process in Canada, as you say, that was our plan from the start as we did not think it would be finished this quick. I will try calling IRCC on Monday.
Again, congrats.
There was a thread (Beijing? HK? don't recall) where someone got PPR and was already in Canada, and there were no instructions about how to do if already in Canada. You might want to check that - I think just called or did webform or emailed VO - and got the answer that it would be switched to in-Canada finalization.
I don't see that you travelling to Canada and then doing the landing there would be an issue. (It would be different if the reverse, eg an inland applicant who was out of Canada).
Perhaps slightly better from an IRCC process standpoint - because perfectly clear - would be for the PA to change flight plans and travel after the citizen. Since there's a pregnancy involved (of the citizen?) - to heck with that.
When you write Paris and/or call IRCC, you could emphasize the pregnancy issue - you really cannot change your flight plans. (Ah note - perhaps not emphasize the pregnancy issue if the pregnant person is the PA).
There's a possibility - small but real - that someone in the VO would decide to deal with this on an urgent basis and have you send your stuff right away and be willing to say that they WILL turn it around as quickly as possible. The problem, as always, is finding that person.
Overall I think it shouldn't be a problem as outland applicants 'land' in Canada all the time, the timing is the primary or only complicating factor here. Good luck.