North Korea didn't acquire nukes to protect itself from the US, it got them to protect its regime from China. It began pursuing nukes in the 80s once its original safeguard against China, its alliance with the Soviet Union, started showing signs it would not be a viable long term strategy.

The anti-US spiel is just rhetoric. It helps save face when dealing with China, which it still utterly depends on, and it goes along with decades of internal propaganda lionizing China to its own people. Indeed North Korea wants heavy US military presence in the region, maintaining its status with regards to China as a strategically important buffer state which can act with plausible deniability instead of a resource rich neighbor with uncooperative leadership.

If North Korea only had conventional forces, what would stop China from installing a loyal puppet? The international community wouldn't lift a finger, threats to South Korea would only further alienate the regime, China could bring its full might to bear, the DPRK military would have no effective means to retaliate and would be more likely to turn on the regime than mount a credible defense, and North Korea's own people would probably welcome the change which would dramatically reduce oppression and increase prosperity. Nukes are the only way for a small number of regime loyalists to make such an operation too costly for Beijing to justify.

This is also why talks with the US have utterly "failed" for decades - there is nothing the US can offer that would provide the same security guarantee for the regime and the status quo is advantageous to the US for multiple reasons: justifying its large military presence in the region, justifying its efforts to develop and deploy ever more capable ballistic missile defense systems, and North Korea not being completely under China's control.