I'm writing a web app where I want users to upload a file, I'll do some processing, and I'll display a result of that processing. AppEngine Blobstore and Cloud Storage allow me to create signed upload URLs server side, and give those to the client to use for upload. This way, I don't have to allow public access to my storage backend, and I don't have to require sign-in.
I've been advised to try Firebase Storage to upload to Cloud Storage, but I don't see this feature in their documentation. Default access is authenticated, or you can make it world-writable. Am I missing something?