Nexus was a part of Silva, but was spun off as an independent entity owned, at least in part, by Dean Baker of America's Cup fame. They seem to be focused on instruments for the yacht racing market, competing against B&G, Ockham, NKE... more so than then the general boating market, which is dominated by Raymarine. ComNav makes parts for them, and was the North American distributor, but about two years ago, Nexus switched to Ocean Equipment
as their North American distributor in an effort to get more widespread distribution over here (e.g. Defender now carries the basic consumer-grade Nexus outfits).
PCP, the Nexus Steer Pilot is just an instrument display with an analog needle that points which way you want to steer - it can be configured to be driven by compass heading, wind angle, GPS track, etc... I think there are some other things it can do, too. It has nothing to do with the autopilot system.