Are you trying to achieve something like below mentioned scenario?
"A marketer or technical specialist will create the campaign workflow. When they place the activity on the canvas, they will need to configure the activity for the specific task. This will include specifying the input and output mappings, API credentials, REST URL endpoint, parameters, etc. The marketers or technical specialist will then run the workflow to verify that the data is being transferred properly."
If yes, then it is possible. You cannot transfer files but you can transfer profile data. However, you cannot use this feature for heavy data transfers. Max Payload is designed to be 5MB. It is not available for transactional messaging.