It's not trading with China that's resulted in Hong Kong's success, but that they were the exclusive intermediary for trade with China for a very long time. North Korea doesn't trade with the West so there's no point in comparing them. There was also a large influx of fortune and human capital that came out of China after the war.
Singapore is more a gateway with Southeast Asia, which certainly has provided it with a great deal of opportunity also, but not nearly to the same extent. I think it would be fair to say to that much of their success is owing to their policy, on a number of fronts.
I also do not mean to say anything about whether Hong Kong has good policy or not. I'm just saying that they would have still been successful regardless, so long as it didn't preclude their role as a trade intermediary. So, even if you were to perfectly recreate all of Hong Kong's policy, you should not expect to get anywhere near the same results. What's generally attributed to the 'genius' of Hong Kong would be much more aptly attributed to dumb luck.
One interesting area where HK has been very non laissez faire is in land ownership. Much of the prime real estate belongs to the government and they can raise money by reclaiming some land and selling it off or renting it out. Also works for Monaco where there is no tax but government controls the real estate. You could argue you could use the same model in the Bay Area to an extent - the government grabs some land, licences fancy blocks for tech workers, auctions off the land with planning permission to builders with the money going to the tax pool. Lower taxes and less accom shortage - win win overall apart from some neighbours complaining about their views.