run yarn in the root directory
copy sample.env into .env and input your drupal url and optionally add basic auth credentials
run yarn start in the root directory
In your Drupal instance install and activate both JSON API and the Gatsby preview module. Spin up a Gatsby Cloud project connected to your git repo, When it has started you will get a preview URL. copy that preview URL intoyour Drupal Gatsby Preview settings. Your changes should be reflected on save.