Good plugin. Needs enabling on all products.

Good plugin. Integrates well. Here’s what I do to enable it on all products by default (weirdly also works for the product creation form) :

add_action('save_post', function (int $post_id, $post_after, $post_before) {
    if ($post_after->post_type === 'product') {
        update_post_meta($post_id, 'qwc_enable_quotes', 'on');
    }
}, 10, 3);