For a while now I have been interested in developing add-ins for Survey123, however I cannot find much in the way of guides or documentation.
What I have found so far looks like a working set of documents.
Any updates from group Admin's?
Survey123 add-ins are not officially supported and have not yet been released as a beta feature via the early Adopter Community. Therefore there is currently no official documentation, and the information you have found in the API reference is the start of some initial beta documentation, however is a work in progress.
For additional information on Survey123 add-ins, please reach out to James Tedrick.