Was briefly mentioned here, but right now I'm at the point where I've connected my GCP project to Firebase, set up a custom domain under Firebase hosting, but on the functions page of the Firebase dashboard, there doesn't seem to be a way to set the vanity URL on a cloud function.
My firebase.json (at the root of my project) looks like :
{
"hosting": {
"public": "public",
"rewrites": [
{ "source": "/helloWorld", "function": "helloWorld" },
{ "source": "/progress", "function": "progress" }
]
}
}