I don't know any VBO, but some time ago I used winSCP command line interface (https://winscp.net/eng/docs/scripting) to transfer file in SFTP. I built command by some calculations and put it in arguments in Start Process stage. I read winSCP logs to confirm that the task was successful. But winSCP has also .NET assembly so it is possible to build a VBO on this basis.
I don't know any VBO, but some time ago I used winSCP command line interface (https://winscp.net/eng/docs/scripting) to transfer file in SFTP. I built command by some calculations and put it in arguments in Start Process stage. I read winSCP logs to confirm that the task was successful. But winSCP has also .NET assembly so it is possible to build a VBO on this basis.