How to get custom page template being edited in gutenberg editor

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You can use this code once set page template for specific post. If the template isn’t set, you cant enqueue your script.

if ( $post->_wp_page_template === 'sky-template.php' ) {
        wp_enqueue_script();
}

Remember to replace sky-template.php with your template file name.

Edit:

You can get some help from this question.
_wp_page_template to dynamically use template