Canada's (mainstream) nationalism is also part of its political left.

I mean it's definitely possible to call yourself that, but I'd argue no, it's not possible to actually be that.

How would you describe North Korea?

DPRK is arguably one of the most successful national socialist states in existence.

(You might look at it and think, "if that is success, then how you define failure"? but don't forget, it took all of 12 years for the German Nazis to go from taking full control to having their country completely devastated.)

In what ways is North Korea socialist? In practice it appears more a hereditary autocracy with an elite class and everyone else barely surviving on the scraps.

German Nazis were socialist in name only, to appeal to the working class.

Just as a note on a historical curiosity, the early NSDAP had a left wing that never seemed to be very important, and they got rid of the corresponding intellectuals (Strasser brothers and friends) even before getting into power, and the corresponding brutes (SA) afterwards.

In exactly the same way as the German Nazis were socialist.

Then you have never studied communist eastern countries and their nationalistic policies.

https://socialhistoryportal.org/news/articles/110357

Famously, Mao Zedong was neither left-wing, nor a nationalist, right?

No-one defines what they mean by "nationalist" so it could apply to a rock.

Here, I’ll define it: nationalist is the idea that nations, including the concept of borders, are a great way to organize people to prevent situations like what Sweden is going through.