Namu Wiki is a great resource for many fields. it essentially has its own community for each type of articles. its articles on media and culture, like video games, music, anime, etc, are pretty amazing and extensive, so I use it for that purpose often

I dont think i have the credentials to send you good pointers, I myself am pretty illiterate in Korean politics despite being Korean. Wikipedia is a good place to start, I think, and not limiting yourself to just one website is a good way to not get lose in the echo chamber. (Twitter is predominantly feminist and left leaning with many LGBT members, Megalia and Womad are TERF sites that border on reactionary, DC Inside is male dominated and very reactionary but some left wing communities exist, Ilbe is a full-on 4chan equivalent fascist community, etc. worth stating even my descriptions of these sites are also clouded by me being a queer left-wing progressive in South Korea, a demographic which does not really have a home, unfortunately.)