There is a 10mm lens available for the Nikon 1 which will give you a 27mm FF equivalent field of view. There are no official lenses wider than that, and finding a lens to mount from another system will be difficult due to the 1 series' small sensor.

The widest rectilinear lenses for APS-C bodies are 10mm, so they're out. Mirco 43rds uses a smaller sensor, so has shorter focal lengths available so something like the Panasonic 7-14mm f/4.0 would be wide enough, however I don't know if a micro 43rds -> Nikon 1 adaptor exists.

It's easier to adapt older fully manual only lenses as you don;t have to worry about electronic aperture control and focus etc. the adaptor is merely a tube which holds the lens at the correct distance. However it will be difficult to find a old lens with a short enough focal length (as ultrawides weren't made for compact formats back in the manual days). So you're best bet might be a fisheye, but that comes with it's own issues.

One option that appears to be viable is a C mount -> Nikon 1 adaptor. The C mount is used for CCTV and machine vision applications, frequently with small sensor cameras so very short focal length lenses are available. However as some of these lenses are designed for low resolution video, the quality might not be up to much on a Nikon 1 body.

If wide angles are your thing, I would consider a system with a larger sensor, such as the Sony NEX line.