These files are configured in a way so that an Ubuntu cloud-image is modified by downloading the RKE2 install script from upstream as well as installing the qemu-guest-agent. This is done so the Ubuntu image can now function in an airgapped environment as an RKE2 node. Previous methods I've done involved using libguestfs tools and it was a bit clunky due to how it needed to be managed. Packer's QEMU provider fixes that for me.
Unfortunately, Packer's QEMU provider must run locally as there is no Harvester provider that would run these commands on a remote Harvester cluster to save us the dependency problem. Perhaps in the future we can explore that level of sophistication, but for now this works great.
There is a post-install provisioner that uploads the resulting image to Harvester using a VirtualMachineImage CR template. If you do not wish to upload to Harvester, feel free to comment out that section in spec.pkr.hcl, it is located towards the bottom and starts with the lines `post-p