How to show price range
I don't think the min max would be readily available in the template and you'll have to add it in.

You could use hook_preprocess_commerce_product($variables) and within $variables it will contain the product entity and also all of its variations. You would just need to loop through the variations to work out the min and max price and then add the new value into $variables e.g.

$variables['min_max_price'] = $myvalue;


Then in your template commerce-product.html.twig do:

{{ min_max_price }}


and that should come out with your $myvalue value