I'm Danish. There are 56k people in Greenland and almost half of them live in Nuuk. The USA could frankly "take" greenland simply by putting a warship there and saying it was theirs. Not really sure why it was ever on the table though. The USA has basically free reign to expand it's military bases there, aside from the ban on nuclear weapons. Sure it would need approval by both Greenland and Denmark, but up until recently we were frankly more allied with the USA than the EU, and I doubt we've ever really said no before. We even bought the damn f35's despite them being so much more expensive than the alternatives, primarily because our history with the F16's. Which would probably have been a possiblity considering we're now debating whether or not to have french nuclear weapon carrying planes stationed on Danish soil in the fallout of the USA no longer being a trusty NATO ally.

If it was because of resources, then American companies are frankly free to extract them as long as they reach deals with Greenland about it. If the USA had waited a few years for Greenland to gain more independence then it would have been even easier.