What is 'Nihilist Penguin' meme that White House shared?

A White House post on X showed US President Donald Trump walking with a penguin towards mountains and a Greenland flag. The post appeared to reference the viral 'Nihilist Penguin' meme. The trend originated from a scene in 'Encounters at the End of the World' documentary that shows a penguin walking away from its colony and heading towards distant mountains.