Welcome to the community!
So far, OnePlus has not partnered with any of the providers in Canada to have their devices tested and certified for use on their networks. Until that happens, it highly unlikely any provider will carry OnePlus devices.
**edit** You should note that since OnePlus devices have not been tested and certified on Canadian networks, certain functionalities (ie Wifi-calling and/or voLTE) won't work**
Hope this helps 😀