For GOS 20.08 a new patch level is available:
https://www.greenbone.net/en/roadmap-lifecycle/
This patch level unlocks EFI/UEFI boot support for virtual GSM appliances shipped with GOS 20.08.2 or later. You may refer to the Roadmap & Lifecycle page for a full list of changes.
Please note the newly added changes of default behaviour regarding virtual machines: https://docs.greenbone.net/GSM-Manual/gos-20.08/en/upgrading-gos.html#virtual-machines.
In addition, the setup requirements for VirtualBox in combination with virtual GSM appliances shipped with GOS 20.08.2 have changed: only VirtualBox 6.1 or newer is supported in these cases.
In total GOS 20.08.2 covers 3 improvements.