When running an interactive service on a Windows 10 and or Windows Server 2016 machine, the Operating System blocks access Session 0 by default.

There is a registry modification that can be carried out to restore access to Session 0.

After modifying the registry, Session 0 is restored and visible again. Although the keyboard and mouse input is still blocked in Session 0 when connected via Remote Desktop Protocol (RDP).

However, this limiation of the Session 0 seems to be limited to Remote Desktop (RDP).
When connected locally from the physcial machine, the Keyboard or Mouse input is not blocked.
When connected remotely from VNC, the Keyboard and Mouse input is also not blocked.