Windows and macOS have similar clients (Hass.Agent for Windows and Home Assistant for macOS).
I’ve found these kinds of clients useful because I can remotely wake-up or sleep computers, track how long they are turned on for, and automatically pause my lights and music when my webcam turns on.
If you’re using it, Home Assistant natively supports Wake On Lan. This would only be able to handle the shutdown/sleep side of things.
Yeah the nodered flow on the target device is for handling shutdown(sleep) and status reporting back to HomeAssistant, so in HA the computer is a simple switch with on/off states