Many people complain about London office on this forum, including me. I withdrew my application and reapplied after moving to a different city, but unlucky me, now London's failure is affecting the closest office to me, which is Niagara Falls.
Yes if you apply for urgent processing and it is approved. However, keep in mind that it takes weeks, now possibly months with the Ukraine situation, before they even read your web form request.
I have first-hand experience. I applied March 2020, received AOR August 2020, processing started October 2020, background completed in January 2021, nothing after that. Sent a withdrawal request in June 2021. Sent another withdrawal request in September 2021. I could see in GCMS notes that they...
Online mid-November applications were getting AORs at the beginning of February, and online mid-December applications are getting AORs 2 weeks later. I do wonder if their application processing will also become faster or if they are simply increasing the backlog.
My family member sent a webform in November, received a response in January; they won't even see your urgent request for over a month. I wonder when they will start using Ukraine and the Act as excuses to delay things after Afghanistan.
I was about to ask why you are creating another thread, but turns out it was another person with a similar question, here: https://www.canadavisa.com/canada-immigration-discussion-board/threads/received-request-for-police-certificate-post-citizenship-application-technically-not-needed.758083/...
The answer is very clear and posted on IRCC's website. "You must have been physically in Canada for at least 1,095 days (3 years) during the 5 years before the date you sign your application." I don't see how that is difficult to understand.
US citizens cannot be denied entry to the US for ANY reason; this applies to most, if not all, countries and their citizens. As long as she can reach a US port of entry and prove she is a citizen to immigration officers, she can enter.