This is really cool, I'm just building an image now. Excited to try it out. One small error is I think you are missing a '\' from the end of line 7 (repository flag)

edit:

I just got this error trying to build an image. Any idea what's wrong or how to fix it?

    ERROR: unsatisfiable constraints:
      novnc (missing):
        required by: world[novnc]
    The command '/bin/sh -c apk add --no-cache chromium   && yarn add puppeteer-core   && apk add   --no-cache   --repository http://dl-cdn.alpinelinux.org/alpine/edge/main novnc' returned a non-zero code: 1

I would super like to try this out! :)