Generally using it that way would be ineffective. Hydrogen has the highest diffusivity of ALL gasses, and it’s the world’s lightest gas… which means it leaves the vicinity IMMEDIATELY and rises to God.
You’d get no value from it unless you seal yourself in a sealed bubble that somehow removes carbon dioxide, adds oxygen and makes sure the hydrogen content does NOT rise above 4% (or you are living in a bomb that even a static spark can ignite).
The cannulas is the only safe and effective way to inhale the BG. Because it’s already in your nose and as you inhale it goes into you instead of out into the air.
Note that 2/3 of the hydrogen goes out into the air anyway (the time you are not inhaling).