You have to make a QCOW2 type image for installation with QEMU:
$ qemu-img create -f qcow2 freebsd_13_10G_ocloud.cow 10G
run the installation:
$ xhost + SI:localuser:root
$ su - root -c 'export DISPLAY=:0.0; qemu-system-x86_64 -boot d -cdrom FreeBSD-13.0-RELEASE-amd64-disc1.iso -m 1024 -cpu qemu64-v1 -hda freebsd_13_10G_ocloud.cow'
Once installed, boot with:
su - root -c 'export DISPLAY=:0.0; qemu-system-x86_64 -boot c -m 1024 -cpu qemu64-v1 -hda freebsd_13_10G_ocloud.cow'
Enable the boot with serial line, for OCloud Console to show the boot. In the FreeBSD OS:
echo 'console="comconsole"' >> /boot/loader.conf
If you need to configure something else is the time before uploading the image. Like a different root user with his Public Key SSH. Once you finish turn off FreeBSD OS.
Now in Ocloud in the menu 'Storage' go to the option 'Bucket' and create a Bucket. In the bucket upload the image.
Now at the 'Compute' menu go to the option 'Custom Images' and option 'Import Image'. In 'Operating System' choose 'Linux', there is no other better option. Select on 'Object Name' the file that Upload to Buckets. In 'Image Type' Configure QCOW2. The most important thing is to select the "emulated mode".
Now go to the 'Compute' menu, to the option' instances', button 'Create Instance', configure the name of your preference. In 'Image and Shape' you have to edit and change the 'Oracle Linux 8' image for your custom image.
All this should work for FreeBSD, but in the boot show the error:
Mounting from ufs:/dev/ada0s1a failed with error 19.
If this can still be solved I do not know.
Also try to install an instance with OpenBSD or NETBSD, but the error was more serious, the kernel does not find the disk controller.