WooCommerce - Disable guest checkout for certain products when Guest checkout is Enabled globally

functions.php

/*--------------------------------------
Woocommerce - Disallow Guest Checkout on Certain products
----------------------------------------*/

// Display Guest Checkout Field
add_action( 'woocommerce_product_options_general_product_data', 'woo_add_disable_gc_fields' );
function woo_add_disable_gc_fields() {
  global $woocommerce, $post;
  
  echo '<div class="options_group">';
  
  // Checkbox
  woocommerce_wp_checkbox( 
  array( 
	'id'            => '_disable_guest_checkout', 
	'label'         => __('Checkout', 'woocommerce' ), 
	'description'   => __('Disable Guest Checkout', 'woocommerce' ) 
	)
   );
  
  echo '</div>';
}

// Save Guest Checkout Field
add_action( 'woocommerce_process_product_meta', 'woo_add_disable_gc_fields_save' );
function woo_add_disable_gc_fields_save( $post_id ){
	$woocommerce_checkbox = isset( $_POST['_disable_guest_checkout'] ) ? 'yes' : 'no';
	update_post_meta( $post_id, '_disable_guest_checkout', $woocommerce_checkbox );
}

// Disable Guest Checkout on Certain products
add_filter( 'pre_option_woocommerce_enable_guest_checkout', 'disable_guest_checkout_based_on_product' );
function disable_guest_checkout_based_on_product( $value ) {

  if ( is_checkout() && WC()->cart ) {
    $cart = WC()->cart->get_cart();
    foreach ( $cart as $item ) {
      if ( get_post_meta( $item['product_id'], '_disable_guest_checkout', true ) == 'yes' ) {
        $value = "no";
      } else {
        $value = "yes";
        break;
      }
    }
  }
  
  return $value;
}

Extended from original code from @mikejolley here: https://gist.github.com/mikejolley/5fadb94dd9eff11ab512
And opposite code here: https://gist.github.com/contemplate/2adc7be2c72d585a07ac6f90b1f1e1b4

Works prefectly!

Awesome, thanks! Is there any way this can be applied to individual product variations? I need to allow guest checkout for an ebook file download, but must disable guest checkout for a LearnDash source.

Adjusted script to only run on checkout by adding is_checkout() && to the condition. We'll see if this still produces desired results.