I have done something similar to GN, but never wrote it down. I think I started with a basic ookie base, but used whole wheat flour, cut bak on some flour, added wheat germ, flax, sunflower seeds, oats, sunbutter for half of the butter, if not more. I also found it crumbly. all the flax and wheat germ do that.
My conclusion is it is hard to have them stick well without some sugar and flour. The more fibrous items you add(ground flax, wheat germ, etc...) the less they stay together. Sugar will melt and create stickiness.
So, the challenge is to do very low on sugar/flour and still stick together.