List of tags/taxonomy on a category page for a custom post type

I have a custom post type (Products), a custom category taxonomy (Product Type), and a custom tag taxonomy (Product Tags). On the Product Type category template (taxonomy-product_type.php) I’d like to display a list of tags that are associated with all entries for that category.

I figured out how to show ALL tags:
‘<?php wp_list_categories( $args = array(
‘show_option_all’ => ”,
‘orderby’ => ‘name’,
‘order’ => ‘ASC’,
‘style’ => ‘list’,
‘title_li’ => __( ” ),
‘taxonomy’ => ‘product_tags’,
)
); ?> ‘

And how to display the tags per each post in the loop:
‘<?php the_terms( $post->ID, ‘product_tags’, ‘Tags: ‘, ‘, ‘ ); ?>’

But what I’d like to do is show a complete list of all tags (outside the loop) associated with the particular category of the page you’re on. I assume I need some sort of custom query? Please help, thanks!