There's some more info on both the NKFD and the BDO at
Germans against Germany in WWII, the NKFD and BDO.
It's interesting that neither organization really had much of an impact. I wonder if the Allies would have dropped the "unconditional surrender" demand and negotiated a peace with a non-Nazi German government that was willing to retreat to 1937 borders (and no doubt make other concessions).