

That depends. Has Russia started a land war across the entire Eastern front at the same time?
Then it might be a bit tough for Europe to do anything about Greenland. It’s almost like the whole ‘we need to take Canada’ rhetoric is pre-emptive, knowing Canada would be the most dangerous remaining opponent to such a plan, should Europe be busy… for some reason. Take Canada and Greenland at roughly the same time. Tie them down while Europe is busy. The US ends up owning Greenland. And, if things fall out wrong, Canada, too - though it might not be a primary goal.
From that point, Russia and the US divide Europe between them.
Is this an insane plan? Yep. Would it work? Doubtful. Is it the potential thinking of the fascist dickheads in charge, despite that? I suspect so.
That can indeed be how memories work (to a certain extent). There are many different types of memory loss. Retrograde amnesia, for example, will often involve retaining a lot of physical skills and lots of knowledge, but no real memories of the past.
The show is, of course, making up fake brain science, but the memory/skill aspect isn’t the magic part.