What spools a turbo is high velocity exhaust gasses. Any way you can get more fuel combusting to make those gasses at launch is a good thing. By dumping a lot of fuel along with nitrous to supply the needed oxygen to burn that fuel, you have instant excess exhaust gasses to spool your turbo. A brake and 2 step do the same thing by dumping excess unburned fuel and oxygen into the headers. Once there, it burns and again, you have some extra exhaust gasses to spool the turbo. Taco farts might even help. It couldn't hurt.

My setup just using the tranny brake and matting the accelerator at the line will make about 7 psi of boost. Not outstanding when compared to what the big guys can do but still it's not too bad when you consider that they sell supercharger kits that put out less than that at peak boost.

I've run supercharged cars and turbo cars. I prefer the turbo cars. I've never run nitrous. No particular reason for that. I just haven't gotten around to it I guess.