Hide specific products from unlogged users based in product category in WooCommerce

I have a certain product category that I only want to offer to logged in users. How would I implement that?

So how to hide specific products from unlogged users in WooCommerce

I've tried searching but It seems a real WooCommerce corner case.

The following code will hide products from a specific product category for unlogged users only. You will have to define in the code the product category SLUG to be excluded in 'terms' array:

// Hide some products from unlogged users and a specific product category
add_filter( 'woocommerce_product_query_tax_query', 'exclude_products_fom_unlogged_users', 10, 2 );
function exclude_products_fom_unlogged_users( $tax_query, $query ) {
    // On frontend for unlogged users
    if( ! is_user_logged_in() ){
        $tax_query[] = array(
            'taxonomy'  => 'product_cat',
            'field'     => 'slug', // can also be 'term_id' or 'name'
            'terms'     => array('t-shirts'), // <=== HERE the product category slug
            'operator'  => 'NOT IN' // Default argument is 'IN'
        );
    }
    return $tax_query;
}

Code goes in function.php file of your active child theme (or active theme). Tested and works.