Idk, it seems pretty straightforward to me? There so much different music genres existing within kpop. You can find retro kpop songs to add to your 70-80s playlist, indie and rnb kpop songs to mix with Western indie and rnb, etc. You can make playlists by vibe ("fun and groovy", "relaxing", "angsty" and whatnot) and add fitting songs no matter the country of origin. Experiment, make different combinations, see what works well together.

I follow three local music industries (Italian, Korean and CIS), I am a fan of Eurovision, I like videogame music, and I follow international English-speaking indie-pop and alt-pop scenes. It's everything and the kitchen sink, but I never had a problem mixing and matching those things into playlists.