You can upload an image for hover effect in products editor. Go to Products > select a product to edit and in “Additional Product Options [8theme]” find the field “Upload image for hover effect” and upload your brand logo.
Do you want to use one hover image for all products?
In this case you may edit the file legenda/woocommerce/content-product.php (line 77), find the code <img src="<?php echo $hoverImg['url']; ?>" and replace <?php echo $hoverImg['url']; ?> with image link.
since I have hundreds of products and more than 20 producers (brands), actually instead of a fixed image link, I need to have a piece of code that retrieves the brand logo image. (I think something like the code you’ve used to retrieve the brand logo in the single product page sidebar). This way each product should have it’s own brand logo image as swap image.