I believe it does apply to the terminal as well as on board:

“When travelling by air, travellers will be asked to cover their mouth and nose:

* at Canadian airport screening checkpoints, where the screeners cannot always keep two metres of separation between themselves and the traveller;
* when they cannot physically distance from others, or as directed by the airline employees; and
* when directed to do so by a public health order or public health official.

Aviation passengers on all flights departing or arriving at Canadian airports will also be required to demonstrate they have the necessary non-medical mask or face covering during the boarding process otherwise they will not be allowed to continue on their journey. “

https://www.canada.ca/en/transport-...-the-canadian-transportation-system.html