Korea has almost every music genre & band, as US or UK or Europe has.
For metal, we have Traditional Metal / Black Metal / Folk Metal / Death Metal / Thrash Metal / ... etc.
For indie music, we have Folk (even 3-40 years ago!) / Post Rock / Techno / Nu Metal / (very little bit) Goth influenced music / ... etc.
Korea has almost every music genre. Just the problem is, there are not too many groups & music market is much smaller than abroad.
So if you want to get recommendation for Korean non-TV music, you must specify what you like.
For example, it's like this.
"Please recommend some Korean metal." (X. I could pick you around 5 bands for the first time, but I can't guarantee you could like most of them.)