We only support cross-compiling on a 64-bit x86 host: http://docs.armbian.com/Developer-Guide_Build-Preparation/
Please be also aware that there are tons of patches added to kernel sources on the fly: https://github.com/igorpecovnik/lib/tree/master/patch/kernel/sun8i-default
One small note that may help others - after reading up a bit on the wifi chip in the NanoPi Neo Air, it is the same Ampak AP6212 that is present in the Raspberry Pi 3. This was helpful as it answered a lot of questions on capabilities, such as an ability to support simultaneous wireless client and AP functionality.
Assuming the following can be ported, it would also likely support monitor mode with frame injection.
https://github.com/seemoo-lab/bcm-rpi3
Another post worth reviewing related to AP-mode operation:
http://tech.scargill.net/size-matters-neo-air/#comment-27039
