Trump has been trying to distract from his backpedaling on all of his campaign promises (massive & stupid tariffs, lowering grocery prices somehow, deporting like 1/4 of the population, etc) before he's even been sworn in by saying he's going to annex/buy/maybe conquer Greenland from Denmark. He's also said this about Canada and sort of about Panama.
The whole thing is a media stunt, but basically, he sent his son and a bunch of other ghouls (pictured in the OP) to Greenland to make an appearance for the media. They did, then they left. It was a fools' errand and there were lots of fools to choose from.
This is not a media stunt. All Danish political leaders have been called in for an emergency meeting later today
Having an ally, and especially your strongest ally, tell you that they can't exclude the possibility of economic or military action against you, is critical, even if it was meant as a joke
He may be using it as a media stunt, but it is having real consequences in the real world already
I like that he keeps saying Canada will become a new state of the United states like it's not a larger land mass than the United states with multiple discrete provinces and territories.