Is it possible to upload a large number of users in ODK Central using a csv file?
We don't have anything user-facing yet, but if you are comfortable in Python, you can use the app user provisioning script at https://getodk.github.io/pyodk/examples.
The script reads names from a CSV and creates an App User for each one that isn't currently used by an active App User on the server. It also creates customized QR codes for each new App User.
You can do something similar for Web Users, but I suppose we can also provide an example if there's interest.