No. NK has a bunch of artillery hidden in the forested mountains just north of the border. And and SK has a lot of population centers within within firing distance. And this includes rockets/missiles with some rather spicy warheads.

And rough terrain ensures that a quick blitz to topple the government and their nuclear arsenal won’t work.

Sure, NK will not be able to hold off SK in the long run, especially if SK invites friends. But Seoul will be leveled.

Plus, China really does not want a US ally on its border, and are likely to intervene.