Iterate through product extras meta in order

pewc-order-meta.php

<?php
function pewc_check_order_meta( $product_name, $item ) {
	if( isset( $item['product_extras']['groups'] ) ) {
		foreach ( $item['product_extras']['groups'] as $groups ) {
			if( $groups ) {
				$product_name .= '<ul>';
				foreach( $groups as $group ) {
					if( isset( $group['type'] ) ) {
					// if( isset( $group['type'] ) && empty( $group['flat_rate'] ) ) {
						$classes = array( strtolower( str_replace( ' ', '_', $group['type'] ) ) );
						$classes[] = strtolower( str_replace( ' ', '_', $group['label'] ) );
						// Display the price
						$price = '';
						$hide_zero = get_option( 'pewc_hide_zero', 'no' );
						// Calculate price
						if( isset( $group['price'] ) ) {
							if( $hide_zero != 'yes' && $group['price'] != '0.00' ) {
								global $product;
								$price = pewc_maybe_include_tax( $product, $group['price'] );
								$price = ' ' . wc_price( $price );
							}
						}
						if( $group['type'] == 'upload' ) {
							$display = sprintf(
								'<li class="%s"><span class="pewc-order-item-label">%s:</span> <span class="pewc-order-item-item">%s</span> <span class="pewc-order-item-price">%s</span><img src="%s"></li>',
								join( ' ', $classes ),
								$group['label'],
								$group['display'],
								$price,
								esc_url( $group['url'] )
							);
							$product_name .= $display;
						} else if( $group['type'] == 'checkbox' ) {
							$product_name .= '<li class="' . join( ' ', $classes ) . '"><span class="pewc-order-item-label">' . $group['label'] . '</span> <span class="pewc-order-item-price">' . $price . '</span></li>';
						} else {
							$product_name .= '<li class="' . join( ' ', $classes ) . '"><span class="pewc-order-item-label">' . $group['label'] . ':</span> <span class="pewc-order-item-item">' . $group['value'] . '</span> <span class="pewc-order-item-price">' . $price . '</span></li>';
						}
					}
				}
				$product_name .= '</ul>';
			}
		}
	}
	return $product_name;
}
// Update with your own filter
add_filter( 'woocommerce_order_item_name', 'pewc_check_order_meta', 10, 2 );