Re: SDDM Wayland

That error is informational only. It has been described as a "totally harmless and entirely misleading message". It informs that the vmwgfx kernel couldn't open the channel for "backdoor logging to host" - which is expected because VirtualBox doesn't implement this functionality, and not related to the real work of the kernel graphics driver. The SDDM login screen does actually display for a couple of seconds, before being dropped to a shell again - something problematic in the SDDM code me thinks. The M$ article you linked to is unhelpful as it only suggests disabling the VM platform - not an option for those using it.