How about Sekihan (I loved his rough vocals, but I don't like his normal voice a lot, but maybe you do) or Vin (I haven't listened to him in a long time, but I liked both his rough and clean vocals I think. I think though in covers where he does rough vocals, he also makes his clean vocals rougher)
Also there's Bis... He can scream to an extent, but has a really nasal voice, so he might not be what you're searching for...
Apparently neko, Yuyoyuppe and Madotsuki@ can too, but I can't guarantee for the quality, because I don't listen to them.
As for other YT singers, I've heard that Nipah, Apol and Kiro do both too, but I can't guarantee anything here either.
Also honorable mentions go to WeatherH. I never heard her doing rough vocals before, but she covers 'harder songs' pretty often, and usually collaborates with other people to do the rough vocals (I think most prominently with horizon), while she does the clean vocals. If you look through her mylist you might find some songs you like, or you might even take a liking to some of her collab partners.
Lol hell I don't know if what I wrote just now was even the slightest bit useful, but I hope so :)