Hello Everyone,
Just to provide my feedback on how it went.
I did land in Montreal and complete the immigration the process at Montreal airport. No issues reported and everything went smoothly with the officer.
It is worth noting that Montreal was a connection to my final destination which was Toronto. At the begining, I thought that I could land in Montreal without completing the immigration process (meaning that the first landing in Canada entry would be at Toronto) but it's not possible since the flight between Montreal and Toronto is a domestic flight.
So even if you transit through Montreal, you will have to complete the immigration process there (i.e your first landing is in Montreal).
Generally speaking, it is not recommended to land in Montreal (Quebec) with express entry due to some issues reported but some people (I did not have any issue and other people did not have any) so if you can avoid it then ok. If there are special circumstances (such as no direct flight available), then it is likely to be ok since you will have a good excuse to give to the officer at Montreal (I was not asked though).
At that time, Canada was in lockdown. I made it clear that my final destination was Toronto with an address to complete the quarantine there.
Retrospectively, I don't think that all these precautions were justified but I was ready with all the necessary arguments to justify why I was landing in Montreal (No direct flight available from Doha to Toronto, connection flight already booked, Airbnb appartment in Toronto already booked, etc.)
My experience is based on Express Entry Federal Skilled Worker. For PNP (provincial nomination), I think it's better to avoid Montreal if your PNP is not for Quebec.
Hope this helps.
Cheers!