A mostly complete example of using gRPC for YouTube's LiveChatMessages: streamList using Node.js. This was my attempt at creating this after about a day of tinkering and research. It's not a complete example, and likely far from perfect, but it should hopefully get you started.

Here's some helpful resources relating to gRPC and Google Cloud in Node.js:
https://grpc.io/docs/languages/node/
https://github.com/GoogleCloudPlatform/nodejs-docs-samples/blob/main/endpoints/getting-started-grpc/client.js
^^^ This shows how to use an API key instead of an OAuth token, as well.