A large number of Harry Turtledove's works were written before Nunavut became a territory. Thus, in most Turtledove timelines involving Canada, Nunavut is either still part of the Northwest Territories, or does not exist at all.
Hudsonia, a province of the North American Union, was, along with Baffin and Banksia, one of the northernmost Provinces of the NAU. Its northeastern tip was a very short sail away from Greenland, a Danish colony.
Confusingly, Baffin Island was part of Hudsonia, not Baffin Province.
The borders of Hudsonia are different from OTL Nunavut. The northwestern section and the King William and Victoria Islands are part of Baffin in the novel's map. However, it includes the southeastern section of the OTL Northwest Territories. Note that Nunavut did not yet exist as a territory when the novel came out.