Take all produts by category

category_name is for category taxonomy, sense products use the product_cat you will need to add a tax_query into $args.
Like this.

$args = array(
    'post_type'      => 'product',
    'posts_per_page' => 20,
    'tax_query' => [
        'taxonomy' => 'product_cat',
        'field'    => 'name',
        'terms'    => 'trofee',
    ],
    'meta_query'     => array(
        'relation' => 'OR',
        array( // Simple products type
            'key'           => '_sale_price',
            'value'         => 0,
            'compare'       => '>',
            'type'          => 'numeric'
        ),
        array( // Variable products type
            'key'           => '_min_variation_sale_price',
            'value'         => 0,
            'compare'       => '>',
            'type'          => 'numeric'
        )
    )
);