PROXMOX configuration: https://ru.man.wikia.com/wiki/%D0%9D%D0%B0%D1%81%D1%82%D1%80%D0%BE%D0%B9%D0%BA%D0%B0_PROXMOX
Stat X server on Proxmox: https://pve.proxmox.com/wiki/Developer_Workstations_with_Proxmox_VE_and_X11
One more X server on Proxmox: https://www.linux.org.ru/forum/desktop/5969900