How to set product brand when programatically importing WooCommerce product?

I am working on a script to import products from a plain text file that is provided to me by a 3rd party. I have successfuly imported the products by using WC_Product object, for instance:

//new product
$objProduct = new WC_Product();
$objProduct->set_status("publish");
$objProduct->set_catalog_visibility('visible');
$objProduct->set_sku($product[SKU]);
//and so on
//edit existing product
$product_id = wc_get_product_id_by_sku($product[SKU]);
$objProduct = wc_get_product( $product_id );
$objProduct->set_status("publish");
//...

The problem I’m facing is that I can’t seem to find a way to add the brand to the products. When importing from a csv file I managed to import the brand by using a code snippet that I found on the web that runs on the woocommerce_product_import_inserted_product_object hook:

public function process_import( $object, $data ) {
      if( isset( $data['product_brand'] ) ){
        wp_delete_object_term_relationships( $object->get_id(), 'product_brand' );
        $brands = explode( ',', $data['product_brand'] );
        foreach( $brands as $brand ) wp_set_object_terms( $object->get_id(), $brand, 'product_brand', true );
      }
        return $object;
    }

I tried using wp_set_object_terms but I get an “invalid taxonomy” error. And I also tried different ways and none of them work and there’s no documentation about it.

These are some of the ways I tried:

$objProduct->set_attributes(['product_brand' => $brandId]); 
$objProduct->set_attributes(['product_brand' => array($brandId) ]); 

$objProduct->set_meta_data(['product_brand' => $brandId]); 
$objProduct->set_meta_data(['product_brand' => array($brandId) ]); 

$objProduct->set_prop('product_brand', $brandId); 
$objProduct->set_prop('product_brand', array($brandId)); 

Any ideas on how can I set the brand? I’m already clueless and got stuck there.

PS: I tried using both, id and brand name (string).

PS2: My script runs on add_action( 'init', function(){//...}) so everything should be available.

Thanks!

Answer

I finally managed to add the custom taxonomy to the product. The problem was that taxonomies were not registered during init hook. I changed it to wp_loaded hook instead. At that point plugins, theme, etc is ready. The method I used to set it is wp_set_post_terms.