You know that WooCommerce generates the Shop page automatically, you only need to select what page to use in the settings.
Also, it does not matter what title your page has, it will still use the title “Product – Your site name”.
How to change it?
Add this code at the end of the file functions.php in wp-content/themes/your-child-theme-name/:
This code will only work on the Shop page and won’t affect any other page in your website.