Finally got the picroft install working on the Googly AIY voice kit using these instructions:
https://community.mycroft.ai/t/mycroft-with-google-aiy-voice-kit-disk-image/
Turns out the image won't work with the Pi3B+, you really want a 3B. Everything starts coming together at that point.
Didn't quite work as a "Good Friday off school" project with the kids, but now we have lots more to play with.