Can understand your pain. If we see it like this - they gave us an immigrant stamp which expires soon and they need us to use it before it expires. This in all means that its for essential purpose.I've read this a few times over, and (to me) the language isn't entirely clear on this scenario. The info seems to state that you can travel to Canada if 1) You're traveling for an essential reason -AND- 2) You're coming from the US -OR- you're exempt for some other reason. This applies to all foreign nationals (including from the US).
I haven't read anything that indicates that landing for permanent residency is considered 'essential.'
However, this page is confusing to me:
https://www.canada.ca/en/immigration-refugees-citizenship/services/coronavirus-covid19/immigration-applicants.html#approved
It says that if you were approved prior to March 18th, you may travel to Canada. That's easy if you have your COPR before March 18th. But I've also read differing opinions as to what "approved" means. Some say it's the date you get your PPR, and others say it's when you get your COPR. Does anyone have any experience with that definition? This could prove pivotal for cases like mine where I got my PPR on March 11. (Assuming, of course, that I get my COPR anytime soon ...)
But yes, final word would be from CBSA and I'd recommend writing or calling them.