Currently, the API V3 endpoints does not have anything for Data Connection Manager (DCM). Create an endpoint to allow users to add/delete/update and list data sources, credentials, and users of DCM data sources. Also include an "admin" endpoint that can list all of the above for the entire server.
The admin screen of Alteryx gallery does not have an admin function for DCM sources, its users, and credentials. This can cause visibility issues during audits of the gallery. An API endpoint can alleviate this issue until it is added to the UI.