Valid point. Node-RED is a successful and popular tool and has a great ecosystem, especially around automation and IoT.

NodeRED is a standalone tool than a "language", and although it's possible, using it to integrate with (and from) existing code is not trivial.

Flyde on the other hand, takes more of a "library" stance. It is agnostic to the code running it and can be easily embedded into other codebases.