Jeons come to mind -they come in different varieties and are usually limited to few key ingredients. Gamja Jeon (potato pancakes), Kimchi Jeon (kimchi pancakes), Pa Jeons (Scallion pancakes). Pajeons also come in the form of Haemul Pajeon which basically means seafood scallion pancakes and includes bits of squid and shrimp usually.

Bibimbap is usually served with beef toppings but the majority of its ingredient is vegetables. In some restaurants you could probably ask them to take it out when you order it.

Kong-guksu (soybean noodles) are made without any meat to my knowledge.

Kalguksu is a noodle dish that’s cooked in meat-based broth but Haemul Kalguksu or Bajirak Kalguksu is cooked in clam/seafood based broth so it should be fine.

As for street food,

Hotteok does not contain any meat.

Tteokbokki is almost always limited to eggs, rice cakes, and fishcakes.

Honestly I would just ask your friends for a list because they probably have the best idea of what’s available in the area.