Populate the <g:product_detail> attribute with the product variation details automaticaly.

wppfm_generate_product_detail_attribute.php

function wppfm_generate_product_detail_attribute($attributes, $feed_id, $product_id) {

	$product = wc_get_product($product_id);

	if (!$product) {
		return $attributes;
	}

	$attribute_names  = [];
	$attribute_values = [];

	$product_attributes = $product->get_attributes();

	// Check wether the attributes are in object or simple value
	foreach ($product_attributes as $attribute_name => $attribute) {
		if (is_a($attribute, 'WC_Product_Attribute')) {
			// Attribute is object
			if ($attribute->is_taxonomy()) {
				$terms = wp_get_post_terms($product_id, $attribute->get_name(), 'all');

				$values = [];
				foreach ($terms as $term) {
					$values[] = $term->name;
				}

				$attribute_label = wc_attribute_label($attribute_name);
				$attribute_value = implode(', ', $values);

				$attribute_names[]  = $attribute_label;
				$attribute_values[] = $attribute_value;
			}
		} else {
			// Attribuut simple value
			$attribute_label = wc_attribute_label($attribute_name);
			$attribute_value = $attribute;

			$attribute_names[]  = $attribute_label;
			$attribute_values[] = $attribute_value;
		}
	}

	if ($attribute_names && $attribute_values) {
		$attributes['product_detail-attribute_name']  = implode('||', $attribute_names);
		$attributes['product_detail-attribute_value'] = implode('||', $attribute_values);
	}

	return $attributes;
}

add_filter('wppfm_feed_item_value', 'wppfm_generate_product_detail_attribute', 10, 3);

Please make sure to remember the following instructions:

This script is designed to automatically populate the <g:product_detail> with the product attributes, including their names and values. To achieve this, you need to add the "product_detail-attribute_name" and "product_detail-attribute_value" attributes to the product feed and populate them with data. This data will be replaced by the script.

If you are not familiar with using filters in your wp-admin, you can easily achieve this by using a plugin such as "Code Snippets" (https://wordpress.org/plugins/code-snippets/). A helpful video demonstrating the use of this plugin can be found at https://www.youtube.com/watch?v=I1_ZqnQmwJs.

Once you have activated the Code Snippets plugin, you can safely use the provided code to add the required functionality.