For Windows, the currently logged in user is called the "console" session. In recent versions of Windows, Microsoft changed the behavior when connecting via RDP to the console user session. For RDC 6.1 and above, the console user is no longer session 0, and /console parameter is no longer used with mstsc.exe for connecting to the console user session.

I would like to make a feature request for FreeRDP to support "shadowing" an existing user session on Windows, particularly the console user.

On recent Windows computers, one can use "query session" to find the session ID of the console user, and then specify the session ID in mstsc using the "shadow" parameter (e.g. session ID 1):
mstsc.exe /v:host /shadow:1 /control /noConsentPrompt /prompt

To do the same in FreeRDP clients, it must implement Windows RDP shadow support. With a shadow connection, mstsc.exe doesn't use the standard RDP port 3389, but negotiates a high TCP port (not sure if this is strictly required).

More info on how it works on Windows is HERE and HERE.