Ability for an external application to retrieve a list of users and their group memberships

We have a requirement from our US head office to provide them with a list of Appian users and what groups they belong to. this is for global access management and audit purposes and they need this data on an ongoing basis. They would ideally like to execute queries from their end as and when required.

Is this possible via running SQL queries on the "core" Appian database tables OR via an API?

If not, could we build a process in Appian to get all users and the groups they belong to, and export that as a CSV file?

thanks