This looks very cool but you should think twice before you use it. If a hacker wanted to infiltrate your LAN, there would be no better way to do it than to provide a tool like this.
> You could make the same argument for other assisted headless installations: speakers, smart plugs, etc.
That's true, but in those devices can be isolated from the internet by a firewall. Berrylan can't be, or it loses its utility. In order to talk to the app, Berrylan has to send packets to and receive packets from the internet. Also, even after the setup, most RaspPi applications entail having the computer continue to have access to the internet. So the situation is much risker with the RaspPi.
You could make the same argument for other assisted headless installations: speakers, smart plugs, etc.