Howard Nurse, W6HN
Looks like you are making great progress getting everything going!
RigPi Hub does not support remote CW keying, but that’s an interesting point. RigPi 2 (in Beta) supports remote CW keying. At the remote end you need at least a Raspberry Pi 0. The RPi can accept keying from a RigPi Keyer board, or from an external keyer. It seems like you should be able to use the N1MM keyer with the RPi 0 to accomplish what you want. It might even be possible for RigPi Hub to be enhanced with a CW keying feature, so you wouldn’t need the RPi 0.
With the current RigPi, the only way to send CW is through the browser you use to access RigPi.