I am using an external agency. Can I prevent changes from being made to my production environment without me first approving it?

As a store owner, you will be able to restrict access to those who may or may not use the StagingPro app through your BigCommerce user permissions. Once you give Administrator rights to the agency, they will be able to send changes to production.

Administrator permissions are assigned to GitHub, so if you have advanced knowledge of GitHub, you could retain admin rights yourself while giving contributor or viewer rights to your agency. Please get in touch with your agency first because this may cause difficulty for your project,