Brand Menu WP All Import - wordpress

Question

I am developing a custom theme for a client of mine selling mainly mobile devices. I am using WP All Import Pro to import products 4 times a day with a cron job and I am updating the stock levels every hour also using cron jobs both from an external xml link.
All that works fine but my client wants a new menu to display all the products by Brand Name.
There are plenty of plugins like WooCommerce brands, yith and perfect brands but they all require me to add the brands manually.
When there are 550+ products and there updated at least 4 times a day this becomes impossible.
I have added the brand in custom fields as you can see in this screengrab...
I have added a menu called brands but there just custom links and go nowhere. I am unsure how to code the brand custom field into this menu. Here is the website I am developing so you have an idea of what's needed..
Many thanks for any pointers you may have.

Answer 1

Instead of a default WordPress sidebar you can use your own custom sidebar with a new custom navigation.
Please, check the following code and you'll see the categories list:
<nav>
<ul>
<?php
$taxonomy = 'product_cat';
$orderby = 'name';
$show_count = 0; // 1 for yes, 0 for no
$pad_counts = 0; // 1 for yes, 0 for no
$hierarchical = 1; // 1 for yes, 0 for no
$title = '';
$empty = 0;
$args = array(
'taxonomy' => $taxonomy,
'orderby' => $orderby,
'show_count' => $show_count,
'pad_counts' => $pad_counts,
'hierarchical' => $hierarchical,
'title_li' => $title,
'hide_empty' => $empty
);
$all_categories = get_categories( $args );
foreach ($all_categories as $cat) {
if($cat->category_parent == 0) {
$category_id = $cat->term_id;
echo '<li>'. $cat->name .'</li>';
$args2 = array(
'taxonomy' => $taxonomy,
'child_of' => 0,
'parent' => $category_id,
'orderby' => $orderby,
'show_count' => $show_count,
'pad_counts' => $pad_counts,
'hierarchical' => $hierarchical,
'title_li' => $title,
'hide_empty' => $empty
);
$sub_cats = get_categories( $args2 );
if($sub_cats) {
foreach($sub_cats as $sub_category) {
echo $sub_category->name ;
}
}
}
}
?>
</ul>
</nav>
Just set the Category (as a brand) for the products and you'll see a simple result.