I did find that kind of funny too! I think the point they're making is that this isn't a full fledged vacuum robot firmware, it's basically the factory firmwar

I did find that kind of funny too! I think the point they're making is that this isn't a full fledged vacuum robot firmware, it's basically the factory firmware patched with a Mi Home cloud emulator/replacement that runs as a daemon on the vacuum. So while you build a firmware image, it's not a fully custom, from-scratch implementation of vacuum functionality, it's just the factory firmware image with the cloud parts replaced.