As a Swede I must confess I don't know much about Greenland. But if Denmark goes all-in on Greenland, you can bet the other Nordic countries will be involved too.
Not sure how this will play out. Really strange situation and as I said I don't even know how much Denmark cares about Greenland. Any Danes here that can tell us more?
"other Nordic countries will be involved"
I can't help wondering if that's really what all of this is about - the Nordics can't really fight the US and Russia at the same time (though given their history I suspect they'd try).
The US has military bases all around Europe from which they would be able to do actions to keep NATO from mobilising.
In 2024 I spent a day protesting outside the Swedish parliament against US base also in Sweden. We warned about Trump probably winning the US election and how unpredictable he is, but the proponents disregarded all our arguments: "Trump being president again? Pfft.. That will never happen", "Provision for US leaving NATO? Pfft. They won't", "Rule against nukes on Swedish soil? Pfft. The US are our friends and will respect our wishes.". The vote passed, and here we are.
I'm Danish, we don't really care about whether or not Greenland is a part of our Kingdom (I'm sure some people do but it's certainly not the majority in my opinion). That being said it's not like it's ours to sell or give away, so it would be more relevant to ask someone from Greenland. I think the most likely outcome is that Greenland decides to leave our Kingdom and become something like the Marshall Isles.
The whole national security part is a lie though. The US can already do whatever they want up there. Well except for having nuclear weapons, but they'd probably be allowed if they asked.
I think some of our politicians care that they'd lose any form of geopolitical relevance without Greenland, but it's not like our population in general supports that.