an update (pasting my last post below for reference!)
i just got a "your application is updated" email, went in and can now see that my BOWP online portal page has my actual UCI and my biometrics info connected. There was also the WP ext letter others have noted receiving. Basically seems like a written confirmation if implied status, and refers to the implied status clause of immigration policy.
Today was the last day of my current WP, and the end date on the letter is 4 months away so I guess they're assuming coverage for the typical BOWP processing time.
paste from the letter:
"This confirms that your application has been received by Immigration, Refugees and Citizenship Canada (IRCC) on [Dec 14th - date I applied]. Please attach this letter to your present work permit Number [doc number of my permit] as proof that you are authorized to continue working with the same conditions (ie: employer and occupation) until April 16th 2021 or until a decision is made on your application, whichever is first. This extended period of work is authorized as per subsection 186(u) of the Immigration and Refugee Protection Regulations. If you leave Canada before a decision is made on your application, you will no longer be authorized to continue working. "
I didn't get an AOR yet. Just the confirmation of online transmission. I called IRCC today and they said AOR will come when they start processing the application (with PR some of this first checks is automatic which is why you get AOR right away for pr). They said the confirmation of online transmission is the minimum you need for implied status.
I also realised right after I submitted that I forgot to attach my PR AOR because there wasn't a document upload field for it.
but I had mentioned in some questions and my LOE that I have a PR app in progress. I had assumed they didn't need it because they asked for UCI etc. Silly mistake. I sent it right away via webform.
part of the reason for calling was panic that I'd get rejected for completeness before the webform is processed as those are taking two weeks these days but the agent said they think it will be fine.