Surface Guntenberg Block in WP Rest API

functions.php

<?php

// Surface all Gutenberg blocks in the WordPress REST API
function add_blocks_to_rest_api() {
  $post_types = get_post_types_by_support([ 'editor' ]);

  foreach ($post_types as $post_type) {
    register_rest_field($post_type, 'blocks', [
      'get_callback' => function (array $post) {
        return parse_blocks($post['content']['raw']);
      }
    ]);
  }
}
add_action( 'rest_api_init', 'add_blocks_to_rest_api' );