Snippet to customize variation dropdown option labels on WooCommerce product page

custom-variation-option-labels.php

<?php

// THIS SNIPPET ADDS CUSTOM FIELD 'price_per_unit' TO THE OPTION LABEL.

add_filter( 'woocommerce_dropdown_variation_attribute_options_html', 'custom_dropdown_args_label', 10, 2);
function custom_dropdown_args_label( $html, $args ) {
    $options = $args['options']; 
    $product = $args['product']; 
    $attribute = $args['attribute']; 
    $name = $args['name'] ? $args['name'] : 'attribute_' . sanitize_title( $attribute ); 
    $id = $args['id'] ? $args['id'] : sanitize_title( $attribute ); 
    $class = $args['class']; 
    $show_option_none = $args['show_option_none'] ? true : false; 
    $show_option_none_text = $args['show_option_none'] ? $args['show_option_none'] : __( 'Choose an option', 'woocommerce' ); 

    $variations = $product->get_available_variations();

    if ( empty( $options ) && ! empty( $product ) && ! empty( $attribute ) ) { 
        $attributes = $product->get_variation_attributes(); 
        $options = $attributes[ $attribute ]; 
    } 

    $html = '<select id="' . esc_attr( $id ) . '" class="' . esc_attr( $class ) . '" name="' . esc_attr( $name ) . '" data-attribute_name="attribute_' . esc_attr( sanitize_title( $attribute ) ) . '" data-show_option_none="' . ( $show_option_none ? 'yes' : 'no' ) . '">'; 
    $html .= '<option value="">' . esc_html( $show_option_none_text ) . '</option>'; 

    if ( ! empty( $options ) ) { 
        if ( $product && taxonomy_exists( $attribute ) ) { 
            
          $terms = wc_get_product_terms( $product->get_id(), $attribute, array( 'fields' => 'all' ) ); 

          foreach ( $terms as $term ) { 
                if ( in_array( $term->slug, $options ) ) { 
                    $html .= '<option value="' . esc_attr( $term->slug ) . '" ' . selected( sanitize_title( $args['selected'] ), $term->slug, false ) . '>' . esc_html( apply_filters( 'woocommerce_variation_option_name', $term->name ) ) . '</option>'; 
                } 
            }
        } else {
            foreach ( $options as $option ) {
                
                foreach ($variations as $variation) {
                    if ($variation['attributes'][$name] == $option) {
                        $unit_price = $variation['price_per_unit']; // or replace with your custom field value
                    }
                }  
                
                // This handles < 2.4.0 bw compatibility where text attributes were not sanitized. 
                $selected = sanitize_title( $args['selected'] ) === $args['selected'] ? selected( $args['selected'], sanitize_title( $option ), false ) : selected( $args['selected'], $option, false ); 

                $html .= '<option value="' . esc_attr( $option ) . '" ' . $selected . '>' . esc_html( $option . ' - Unit Price: ' . get_woocommerce_currency_symbol() . $unit_price ) . '</option>'; 

            }
        } 
    } 

    $html .= '</select>'; 
    return $html;
}

?>