Welcome to the community!
You can certainly request your phone number to be ported over to Fido. However, you should note that your phone number's region would have to remain the same. The area codes, by definition, are designated by a region or area. In addition, the area code and prefix combination determine the local calling areas (LCAs; see here). Since porting your phone number does not change the area code nor prefix, your phone number would remain a Montréal phone number.
If you would like to obtain a Vancouver phone number, you would need to select one with an area code and prefix from that location.
You should note that while many of Fido's plans include Canada-wide calling, some plans might only include Provincial or local calling. If you ported your phone number and are living in Vancouver, you might need to consider what entails long-distance.
Your incoming local-calling area (LCA) is based on the geographical location that is associated with your number. It has nothing to do with your own physical location at the time you receive a call. On the other hand, your outgoing LCA is determined entirely by your physical location at the time of a call, and has no ties to any specific geographical location, other than the one in which you’re standing.
All incoming and outgoing calls are considered airtime. Receiving calls while outside of your incoming LCA is considered LD. Making calls while travelling can either be local or LD, depending on whether the call destinations are within or outside of your outgoing LCA.
If you would like to port your phone number from your previous provider, you would need to ensure the line remains active for the porting process (see here). Once your number has been successfully ported, your line with your previous provider would automatically get cancelled.
Hope this helps 😀