My cheap air impact wrench with 125lbs of pressure would not work. You'll need their heavy duty model. I would first try Steve.
Key to impact is restricting movement, what I mean by that, the blows are short travel and peak at the beginning. The comment about Sprocket jammer failing, I have never see a deep socket fail ever, the trick again is putting bike in neutral , I put a small piece of wood under the rearmost part of my rear tire, this kept tension on the sprocket. I have both electric and air impacts, the air I ran up to 125 LBs, 4 seconds and the nut was off. The electric took about 20 seconds from what I remember on the 07, when I sold the 07 I took my 16T off and put the OEM back on. Same with my 2015. Another way of explaining it, immagine a double nut on a shaft , mounted on bearings, you get buddy to hold a large wrench with a pipe on the wrench, you get the same, the force on the nut , is equal to the lesser of the forces between you two. By having a preload on the deep socket using the chain and tire only, in neutral, the peak force from the impact will break the nut loose.
One caution, you should never use heat on something like this as the shaft is hardened and the seal could get damaged, using heat will anneal the shaft. Also in reference to heat, you need a oxyacetylene torch or a oxy-propane torch , two people and you only have about 5 seconds, I say two people because by the time you set the torch down / shut it off, you have lost over 5 seconds, during this time heat is penetrating the shaft, once that is hot expansion is occurring. If you really have something that is stuck and it is extremely valuable or hard to source, use dry ice , pack it , insulate it, wait about a hour, be aware that metal becomes brittle below minus 50'C.
You now can apply heat, FYI freezing takes much longer to take place, remember you are removing energy, it takes much longer for heat to tranfer when applying to either dry ice or liquid nitrogen.
Here is the proper way using liquid nitrogen;
And here is a really risky way of doing it using heat, and almost a joke using a chain operated chain hoist, note around 2:45 they almost lose it, had to pull up as it was jamming. For those interested , that is K Wool, rated for 2300'F , I use that for soldering near flamable materials, it is used in the foundry industry.