East Germany had no choice but to agree to immediate reunification with the West to stave off complete economic collapse,
North Korea isn’t at that point yet.
North Korea managed to infiltrate, on a worldwide basis, every area of criminality you can think of. Their economic collapse just wasn’t going to happen.
I'm not so sure we know for sure. The East Germans were not willing to eat tree bark and make bread from grass and weeds, so huge difference in what their respective populations were able to endure.
Also (to argue in favor of your point) North Korea's big sponsor is the second largest economy in the world. Russia did not come anywhere close for East Germany in said role and was itself living on borrowed time by November 1988.