lambda-stream.js

const { createReadStream } = require("fs");

api
  .get({ Bucket, Key })
  .createReadStream() // read zip file
  .pipe(unzip.Parse())
  .on("entry", (entry) => {
    // stream it further and use entries inside
    if (entry.type !== "Directory") {
      const uploadOptions = {
        Key: outputKey,
        Bucket: Bucket,
        Body: entry, // readableStream
        ACL: "public-read",
      };

      return api.upload(uploadOptions).promise();
    } else {
      entry.autodrain();
    }
  })
  .on("close", () => {
    callback(null, "All done!"); // Inform lambda that it can finish execution.
  });

Also see: https://github.com/pavelloz/streams-vs-buffers