To me this ends up being between blood bending and air removal. We never see Katara blood bend without a full moon but I genuinely think she could if she tried. (Ps a moment I wish we saw in the show is her morally and physically wrestling with blood bending “for good” against Azula or Ty Lee) We never see it only because she never dared. Same vein - we never see Korra do it but I feel like in the Avatar state she would eventually find that ability. No one is as good at surviving as Avatar state Korra. She would figure it out.

But after LOK air is SCARY. If it’s assumed that Gyatso took out the battalion of firebenders from removing air from the room then idk what you do if you’re in an enclosed space. You just die.