Triggering automation in Node Red via Homekit

Any thoughts on how I would go about using Homekit in HA to trigger an automation in Node Red?

What exactly do you mean? Like pressing an entity in homekit and execute it nodered?
Nodered can receive webhooks that trigger flows. You can create a ha script that curls the webhook, that script can be exposed to HomeKit.
I guess you can do the same with an input_boolean exposed to HomeKit and then nodered acts on change of state.

The input-boolean is exactly what i am doing.
It works like a charm.