Short answer: no. NK submarines, even the model capable of launching ballistic missiles, are diesel-electric boats. They would need a network of tenders/mother ships to help them reach launch areas in the central and eastern Pacific. That sort of activity would certainly attract the attention of the USN.
Additionally, NK subs are noisy in comparison to newer diesel-electric boats and easier to track. It’s not a stretch to think that any DPRK missile sub enroute to a launch position would be dispatched by a P-8; an ASW helo, a surface vessel or even a Los Angeles or Virginia-class attack boat.
The real problem with North Korean SLBMs is that as the technology improves, range and accuracy will improve. At some point, Pyongyang will have long-range missiles than can be fired by subs in “bastion” locations in the Yellow Sea or Sea of Japan. Operating from home waters, it is much easier to protect the boomers and for those systems to initiate a first strike.
Really appreciate the thorough answer.
Seems like NE Asia is in much more danger than our coasts - at least from their subs.
As technology improves certainly. I think with a nuke you could be a bit off target and yield the desired result.