I've been experimenting with singing a note and then slowly devoicing it or applying less pressure with my, usually near the top of my chest / modal(?) register, and trying to get that harsh sound where it sounds like there's a two tones plus a bunch of noise / interference. I'm not a vocalist, so I don't know what this would be called, but it reminds me of multiphonics (both on bowed string instruments and wind instruments). I tried searching for the term "vocal multiphonics", but that's already taken by brass players.
I don't think it's screaming, and it doesn't feel like creaky voice. Yodeling seems close, but that would involve flipping completely between registers rather than staying in between. So what is it called?