You’re looking for the user list?
You can use the sync_sso API as described here: Sync DiscourseConnect user data with the sync_sso route
I’m not sure about whether updating a record using sync_sso
obeys sso_overrides_name
- you’ll need to test that.
You can always use the Admin API - I would first define your workflow and then search through the API to find the API endpoints you need to call to accomplish your goals - they’re all there.