Raspberry Pi 4 image + Node-RED GOOGLE_CLOUD_PROJECT variable

Following https://flows.nodered.org/node/node-red-contrib-google-cloud
I want to set the GOOGLE_CLOUD_PROJECT variable to be used by Pub/Sub to receive events from Google Device Access.
Where/how do I see this variable to point to my GCP project?
Home Assistant and Node-Red are running in seperate containers. (all deployed as addons via the Hassio RPI4 image)