How to boot Partitionless on Openstack?

I just migrated a virtual machine from Linode Cloud to Openstack via Veeam Agent. But when I boot up I see the problem, the screen shows "*Boot failed: not a bootable disk...No bootable device...*". As far as I know about Linode Cloud, they are deploying VMs with partitionless. 1. https://www.linode.com/docs/guides/install-nixos-on-linode/ 2. https://gist.github.com/ZeroDeth/b583dffa50768bce595e10dc13a64b96 I have tried everything I know, such as reducing the partition size to make room for the boot partition, but all attempts have been unsuccessful.