The hurdle Noveau is facing is that some things, like reclocking, need firmware loaded onto the card. The firmware is not in non-volatile memory on the hardware, but a file shipped with drivers, the one shipped with proprietary drivers is not redistributable and if you wanted to make your own, it needs to be signed by Nvidia anyway.

That's pretty much game over for Noveau, and it is not due to difficulties in figuring out registers and NV ISA.