Create a new Oracle Linux VM. You can disable in-transit encryption, as encryption will be implemented at the OS level with dm-crypt. Connect to the VM with SSH (you can't connect from the Cloud Shell as the opc user has no password). Then, run the following to reboot the VM into Alpine Linux:
sudo su
wget https://dl-cdn.alpinelinux.org/alpine/v3.15/releases/aarch64/alpine-virt-3.15.0-aarch64.iso
dd if=alpine-virt-3.15.0-aarch64.iso of=/dev/sda; sync
reboot