We have a Drupal 8 site hosted at Pantheon and the site configuration is locked via the "Configuration Read-only" module.
I created a local clone of the site using git and added a new user but when I do a git status it shows my branch as being in sync with the master. With this said, it doesn't look like the newly added user was written to any of the config YAML files.
So, I suspect that I will need to export the database from my local and import it to Pantheon - but this doesn't seem like the correct process or safest method. Can someone please confirm as I haven't found any resources applicable to this scenario and want to ensure that I'm following best practice?
Users are Entities and as such are stored in the database, not in configuration.
If you want to synchronize your users across different environments then you'll have to look into a way to retrieve db backups from Pantheon and import them into a different environment or look into a module to sync the User entities. I found the content_sync module from a quick Google search, but have not used it and cannot guarantee that it will work/ fulfill your requirements.