Adding an external link to product grid list pages for woocommerce

A possible hook to position a button in that point is woocommerce_after_shop_loop_item:

add_action("woocommerce_after_shop_loop_item","Stack_308575_add_button",99);

function Stack_308575_add_button(){
  global $product;
  echo "<button onclick=\"alert(".wc_get_product($product)->id.")\">Click</button>";
}

If you need dynamic links you can get the global $product object and retrieve data from there