In order to list VMs on the command line, login to XCP-NG using SSH and run this command:
xe vm-list
Example output:
[16:51 virt01-xcpng ~]# xe vm-list uuid ( RO) : 56dc99f2-c617-f7a9-5712-a4c9df54229a name-label ( RW): VM 1 power-state ( RO): running uuid ( RO) : 268d56ab-9672-0f45-69ae-efbc88380b21 name-label ( RW): VM2 power-state ( RO): running uuid ( RO) : 9b1a771f-fb84-8108-8e01-6dac0f957b19 name-label ( RW): My VM 3 power-state ( RO): running