Add custom product info to Additional Information tab - Use CMB2 to add a custom metabox to WooCommerce product then add data to Additional Information tab on product page. https://www.damiencarbery.com/2020/03/add-custom-product-info-to-additional-information-tab/

cmb2-add-book-info-fields.php

<?php
/*
Plugin Name: Add custom product info to Additional Information tab
Plugin URI: https://www.damiencarbery.com/2020/03/add-custom-product-info-to-additional-information-tab/
Description: Use CMB2 to add a custom metabox to WooCommerce product then add data to Additional Information tab on product page.
Author: Damien Carbery
Author URI: https://www.damiencarbery.com
Version: 0.4
*/


add_action( 'cmb2_admin_init', 'dcwd_wc_book_info_fields_metabox' );
function dcwd_wc_book_info_fields_metabox() {
	$cmb = new_cmb2_box( array(
		'id'            => 'book_info',
		'title'         => 'Book Information',
		'object_types'  => array( 'product', ), // Post type
		'context'       => 'side',
		'priority'      => 'default',
		'show_names'    => true, // Show field names on the left
	) );
	$cmb->add_field( array(
		'name'        => 'ISBN13',
		'id'          => 'isbn13',
		'type'        => 'text',
		/*'attributes' => array(
			'required' => 'required',
		),*/
	) );
	$cmb->add_field( array(
		'name'        => 'ISBN10',
		'id'          => 'isbn10',
		'type'        => 'text',
		/*'attributes' => array(
			'required' => 'required',
		),*/
	) );
	$cmb->add_field( array(
		'name'        => 'Pages',
		'id'          => 'pages',
		'type'        => 'text_small',
		'attributes' => array(
			'type' => 'number',
			'pattern' => '\d*',
			//'required' => 'required',
		),
		'sanitization_cb' => 'absint',
			'escape_cb'   => 'absint',
	) );
	$cmb->add_field( array(
		'name'        => 'Author',
		'id'          => 'author',
		'type'        => 'text',
		/*'attributes' => array(
			'required' => 'required',
		),*/
	) );
	$cmb->add_field( array(
		'name'        => 'Publisher',
		'id'          => 'publisher',
		'type'        => 'text',
		/*'attributes' => array(
			'required' => 'required',
		),*/
	) );
	$cmb->add_field( array(
		'name'        => 'Publish Date',
		'id'          => 'publish_date',
		'type'        => 'text_date',
		/*'attributes' => array(
			'required' => 'required',
		),*/
	) );
}


// Add the book information to the Additional Information tab.
add_action( 'woocommerce_product_additional_information', 'dcwd_book_info_in_additional_info_tab', 20 );
function dcwd_book_info_in_additional_info_tab( $product ) {
	$product_post_meta = get_post_meta( $product->get_id() );

	// Post meta field => Label.
	$book_info_fields = array( 'isbn13' => 'ISBN13', 'isbn10' => 'ISBN10',
							   'pages' => 'Pages', 'author' => 'Author',
							   'publisher' => 'Publisher', 'publish_date' => 'Publish Date' );
	$book_info = array();
	foreach ( $book_info_fields as $key => $label ) {
		if ( array_key_exists( $key, $product_post_meta ) ) {
			// Display the label and then the data.
			$book_info[] = sprintf( '<strong>%s</strong>: %s', $label, $product_post_meta[ $key ][ 0 ] );
		}
	}
	echo '<p>', implode( '<br />', $book_info ), '</p>';
}


// Verify that CMB2 plugin is active.
add_action( 'admin_notices', 'verify_cmb2_active' );
function verify_cmb2_active() {
	if ( ! defined( 'CMB2_LOADED' ) ) {
		$plugin_data = get_plugin_data( __FILE__ );
		$plugin_name = $plugin_data['Name'];
?>
<div class="notice notice-warning is-dismissible"><p>Plugin <strong><?php echo $plugin_name; ?></strong> requires <a href="https://wordpress.org/plugins/cmb2/">CMB2 plugin</a>.</p></div>
<?php
		//error_log( 'CMB2 is not active.' );
	}
}