Example of how to create a taxonomy dropdown filtered by WooCommerce Product Category we are currently on.

archive-product.php

<?php
//Put this code in your child theme inside the woocommerce folder or add it with a filter.

// Get currenty category ID
$cat_id = get_queried_object_id();

// Get Location terms filtered by Product Category of this page.
$post_ids = get_objects_in_term( $cat_id, 'product_cat' ); // WooCommerce default category
$terms = wp_get_object_terms( $post_ids, 'location' ); // Custom Taxonomy for WooCommerce Products

// Put them in an array like this: [slug]=>"name"
$terms = array_combine(
	wp_list_pluck( $terms, 'slug' ),
	wp_list_pluck( $terms, 'name' )
);
?>

<select name="location" id="location">
<?php
  foreach($terms as $key => $term) { 
    echo '<option value="' . $key . '">' . $term . '</option>';
  }
?>
</select>
<input class="SubmitButton" type="button" value="Show" onclick="showProducts()"/>

example.js

function showProducts() {
		var loc = document.getElementById('location');
		var option = loc.options[loc.selectedIndex].value;
		location.href = window.location.href.split(/\?|#/)[0] + '?location=' + option;
	}