Find below information from IRCC (India specific)
https://www.facebook.com/notes/canada-in-india-high-commission-of-canada/frequently-asked-questions-immigration-related-queries/3287734844612460/
Confirmation of Permanent Residence - Immigration visa (IM-1)
If your application for permanent residence was approved on or before March 18, 2020, but you have not travelled to Canada yet, you’re exempt from the travel restriction measures. Eligible travellers do not require additional permission letters.
If your counterfoil expires prior to commercial flights becoming available, you do not need to e-mail IRCC as you will receive communication from our office on the next steps to be taken once full-service resumes.
What does full service resumes mean ? When Corona vaccine is out ? Logically 'full service' can only resume when the virus is under control or vaccine is out .As per my understanding they will issue new PPR for stamping only after they resume full service.
Any ways lets hope for the best !!