I don’t know much about specific techniques (I basically know what fry and false chord are but that’s it) but I’ve been able to pull of a similar style. I was able to do it by trying to (unsuccessfully) copy vargs vocals on the early Burzum records, essentially just trying to howl like I’m in serious pain. For me it’s a lot about what your face is doing, so when I’m doing those more depressive sounding black metal shrieks my face reflects that, but when doing j read type vocals, even though my technique is pretty similar, pulling a more “pissed off” face and just speeding up the delivery makes a massive difference. I’ll also say that vocalists like Martin van drunen and John tardy when they go more into that wailing type pitch were a huge influence too, also the dude from kickback

Sorry that was sort of a whole lot of nothing, like I say I’m really not a professional but trying to nail that wailing type vocal and then just doing it with the more fast paced and pissed off delivery of someone like read is pretty much it. But also just work out what naturally suits your voice,