Create a custom post type gist for my WordPress: tutorial "Multiple Custom Templates for Posts and Custom Post Types" at https://since1979.dev/wordpress-multiple-custom-templates-for-posts-and-custom-post-types/

create-custom-product-post-type.php

<?php
function create_product_post_type() {
  register_post_type( 'product',
    array(
      'labels' => array(
      'name' => __( 'Products' ),
      'singular_name' => __( 'Product' )
    ),
      'public' => true,
      'has_archive' => true,
      'show_in_rest' => true // To enable Gutenberg.
    )
  );
}

add_action( 'init', 'create_product_post_type' );