I remember about 10 - 15 years ago, when sushi was really taking off in my area, a good friend was at a sushi bar and literally saw the worms crawling out of his raw fish. He swore it off for 10+ years and only occassionally abides now. I think I recall people getting some form of parasite from sushi about the same time.
Not specifically pig kidney but … steak and kidney pie is very common in England. You will find it eaten in lots of different cultures. I’d be shocked if Koreans do not eat kidney.
+1 on sea cucumber. Nasty things to handle but taste great when prepared right. A nice flavorful sake is good when the meat is prepared simply with vegetables in broth.
Found worms in my fresh fish a few years ago. Took it back and the fish guy said that it’s not too uncommon and that they die when you cook the fish so it’s not a problem. We returned the fish anyway and had steak that night.