I haven't found any GUIs that support Oracle Cloud Storage. I would love support in WinSCP.
Do you want to use WinSCP GUI or scripting? If GUI, were you able to use any GUI S3 client against the Oracle Cloud? GUIs have different requirements than command-line clients.
I'm currently using RCLONE to sync files.
I did some tests. While I was able to connect and see the buckets, I could not see files nor I was able to transfer any. But I had similar problems even with other S3 clients. It does not look like Oracle Cloud has good compatibility with S3. Were you able to use any S3 client against Oracle Cloud successfully?
What kind of support does it need? If Oracle supports S3, you should be able to just specify the Oracle endpoint on WinSCP login dialog.
Would it be possible to add support for Oracle Cloud Object Store S3 buckets?