Yes rattle guns be it electric or air are the answer to removing tight retaining nuts, especially if the shaft can't be locked. ( plus heat where required) But I prefer to use either a torque wrench or good old-fashioned feel for assembly.
I spent many years working on heavy earth moving equipment, 3/4"and 1" drive sockets being in common use. When on site with no power, air or electric, no battery tools back then, I had a hand operated torque multiplier, 3/4" drive in, 4 to 1 reduction, 1"drive out. This was a good piece of kit, especially in confined spaces. I still have it in it's box under the bench, and hopefully that is where it will remain