@vercel/gatsby-plugin-vercel-builder/gatsby-node.js

This plugin generates [Vercel Build Output API v3](https://vercel.com/docs/build-output-api/v3) for Gatsby v4+ projects.

const { generateVercelBuildOutputAPI3Output } = require('./dist/index.js');

exports.onPostBuild = async ({ store }) => {
  await generateVercelBuildOutputAPI3Output({
    // validated by `pluginOptionSchema`
    gatsbyStoreState: store.getState(),
  });
};