For me node-red is more of an addition to homeassistant. There is node-red-contrib-home-assistant-websocket [1] to let node-red speak with homeassistant, you can watch state changes etc. I use ha for like two years now and at the start there was no inbuild automation-backend like it is now so we did everything with node-red.

https://flows.nodered.org/node/node-red-contrib-home-assista...