Hi kreativeabu,
Thanks for details.
1. Mega Menu
You can create a dev site and import any template there, then with the help of the import functionality of Elementor you can export HTML Blocks, more detail is here: https://elementor.com/help/template-library/
Devsite – also called a Staging platform where you can test issues, enable/disable features/plugins thus such changes will affect the main site. The below article will help you to create it:
https://www.wpbeginner.com/wp-tutorials/how-to-create-staging-environment-for-a-wordpress-site/
Then, please read our documentation on how to import/export header:
https://xtemos.com/docs-topic/how-to-export-import-headers/
https://xtemos.com/docs-topic/create-mega-menu/
2. Single product
You are using a Custom Single Product layout, which is built with WoodMart WooCommerce builder. Navigate to Layouts > Layout to edit Single product layouts and content.
Further, you can read more about the Layout Builder here: https://xtemos.com/docs-topic/woodmart-woocommerce-layout-builder/
Best Regards