Ubuntu on z, is an Ubuntu Server and Cloud offering, that is by default it is headless systems, without any graphical displays. No graphical Desktop Environments. The default experience of Ubuntu Server, Cloud, OpenStack, Juju, LXD, MAAS use command-line and web-app interfaces.
As there is no display, before using VNC, one must create one. However, I discourage you from using graphical apps. What applications and workloads are you trying to use, that require a display and/or remove VNC display?
Ubuntu on z, is an Ubuntu Server and Cloud offering, that is by default it is headless systems, without any graphical displays. No graphical Desktop Environments. The default experience of Ubuntu Server, Cloud, OpenStack, Juju, LXD, MAAS use command-line and web-app interfaces.
As there is no display, before using VNC, one must create one. However, I discourage you from using graphical apps. What applications and workloads are you trying to use, that require a display and/or remove VNC display?