How to Create a Custom Product Type in WooCommerce: A Step-by-Step Developer Guide

<?php
/*
Plugin Name: Custom Product Type
Description: Adds a custom product type to WooCommerce.
Version: 1.0
Author: Your Name
*/

// Hook for initializing plugin functionality
add_action('plugins_loaded', 'custom_product_type_init');

function custom_product_type_init() {
    // Define Your Custom Product Type Class
    class WC_Product_Custom_Type extends WC_Product {
        public function __construct($product) {
            $this->product_type = 'custom_type';
            parent::__construct($product);
        }

        public function get_type() {
            return 'custom_type';
        }
    }

    // Register the Product Type with WooCommerce
    add_action('init', 'register_custom_product_type');
    function register_custom_product_type() {
        if (class_exists('WC_Product')) {
            class WC_Product_Custom_Type extends WC_Product {
                public function __construct($product) {
                    $this->product_type = 'custom_type';
                    parent::__construct($product);
                }

                public function get_type() {
                    return 'custom_type';
                }
            }
        }
    }

    // Add Product Type to Dropdown
    add_filter('product_type_selector', 'add_custom_product_type');
    function add_custom_product_type($types) {
        $types['custom_type'] = __('Custom Type', 'text-domain');
        return $types;
    }

    // Add Custom Fields and Options
    add_action('woocommerce_product_options_general_product_data', 'add_custom_fields');
    function add_custom_fields() {
        global $woocommerce, $post;
        echo '<div class="options_group">';
        woocommerce_wp_text_input(array(
            'id' => '_custom_field',
            'label' => __('Custom Field', 'text-domain'),
            'description' => __('Enter the custom field value.', 'text-domain'),
            'desc_tip' => 'true',
        ));
        echo '</div>';
    }

    // Save Custom Fields Data
    add_action('woocommerce_process_product_meta_custom_type', 'save_custom_fields');
    function save_custom_fields($post_id) {
        $custom_field = isset($_POST['_custom_field']) ? sanitize_text_field($_POST['_custom_field']) : '';
        update_post_meta($post_id, '_custom_field', $custom_field);
    }

    // Modify the Product Display
    add_action('woocommerce_single_product_summary', 'display_custom_field', 20);
    function display_custom_field() {
        global $post;
        if ('custom_type' === get_post_meta($post->ID, '_product_type', true)) {
            $custom_field = get_post_meta($post->ID, '_custom_field', true);
            if (!empty($custom_field)) {
                echo '<p>' . __('Custom Field Value: ', 'text-domain') . esc_html($custom_field) . '</p>';
            }
        }
    }
}