it's a bit of a blurry distinction because, what is firmware if not the software that runs on an embedded device? a more accurate description would be that the high-level operating system (HLOS) has been modified to include the installation of a drop-in-replacement for the cloud API. the client side, and whatever hardware abstraction layer lives below it, is untouched. so the client thinks it's talking to the server but it's actually talking to a local open-source server.

I think it's also not quite correct to say the low-level firmware is unmodified, because with vale tudo you rely on the project author to provide a minimal rootkit that gets customized on a per-serial-number basis for the initial rooting.

from a high-level though, it delivers what it says on the tin - cloud features without any requirement of packets leaving your network or even the robot itself.

here's a talk from the author discussing his research https://www.youtube.com/watch?v=AfMfYOUYZvc