PowerShell Direct is a feature that was rolled out with Windows 2016 and Windows 10 that enables you to interact with a virtual machine (VM) that you have running inside Hyper-V even if that VM isn't connected to the network.
It's a great time saver as you can issue commands and carry out tasks without having to log into the VM.
As I mentioned you don't have to have the virtual machine connected to a network in order to interact with it, ask log as you have guest credentials for the VM you can run the commands against it. So this is not a mechanism you can use to bypass the VM's security, only those that have the credentials can log in. Think of this as a great way of trying to troubleshoot a VM if there is a network connection error or misconfiguration.
Some of the PowerShell Direct commands are slightly different than the ones you might be familiar with if you are using to PowerShell remoting.