Unfortunately using the .com always displays a console window and there seems no way to suppress this.
No, the
winscp.com inherits a console of the parent batch file.
                
            Unfortunately using the .com always displays a console window and there seems no way to suppress this.
winscp.com inherits a console of the parent batch file.
                
            WinSCPportable.exe here.
winscp.exe behaves as you want. And the proper WinSCP is portable too anyway, no need to use the 3rd part "WinSCP portable" project.
winscp.com from a batch file, instead of the winscp.exe.
call command to launch winscp.exe.