There was a similar hack for nikon but it has been deleted off the internet. Its only for a few cameras now. I have been waiting for a hacked firmware for so long because P900 is a point and shoot but can perform better. I've read that Nikon firmware is very difficult to crack and so far no one has been able to reach even close to the chdk type of firmware for Nikon.
For the image quality, I have set it to FINE instead of NORMAL that it was by default. Looks like this is the best image I will get. However, I tried stacking 640x480 images that I took while taking burst shots and they stacked surprisingly well. No distortion, no blocks, just a clean image at the end. But ofcourse, that image was of no use because it was so low res to begin with anyway