One of the less well known missions of the Canadian Coast Guard is to resupply some of the smallest detachments and posts in the Arctic. Although the north seems vast, there is perilously little infrastructure like conventional harbour facilities. Air freight is expensive, so almost everything else has to be delivered in the 30 or 60 days of safe shipping.
Loads are assembled through the winter in Montreal, Quebec City and other ports then loaded onto coasters that are escorted by government icebreakers. At destination, cargo is transferred over the side into boats to be landed as best it can. I have seen pictures of huge front end loaders wading out into lightly iced harbours to move cargo in their buckets. For the CCG to have landing craft is only one way of delivering the goods. Rankin Inlet, Churchill and Iqaluit come to mind as having port facilities, but the other dozen or fifteen northern settlements are much less well served - except for spectacular geography and isolation.
Getting back to the original question, I doubt the boats illustrated are ex-military, but very likely inspired by WWII lessons. Every so often work boats and other vessels come up for sale on Crown Assets.
https://www.gcsurplus.ca/mn-eng.cfm?...1&sf=ferm-clos