So I have created a OpenBSD 7.3 VM in libvirt with the following shell command.
virt-install --name openbsd7.3 --os-variant openbsd7.0 \
--virt-type kvm --vcpus 1,maxvcpus=2 --memory 256,maxmemory=512 \
--disk /home/dev/Downloads/ISOs/install73.img,boot.order=1,format=raw \
--disk /home/dev/Dev/VMs/openbsd7.3/openbsd73.img,boot.order=2,size=10 \
--cpu host-passthrough --boot uefi --import;
Then I completed the installation, removed the installer disk while VM was up.
virsh detach-disk --domain openbsd7.3 ~/Downloads/ISOs/install73.img \
--persistent --config --live
Then I setup sudo and vagrant user, insecure public key on the VM.
After completing the steps, I generated a openbsd73.box file from openbsd73.img with the create_box.sh script from vagrant-libvirt github repo.
And then I added the .box to vagrant with
vagrant box add openbsd73.box --name openbsd73
After it was successfully added to Vagrant, I created a Vagrantfile to test it with
vagrant init openbsd73 && vagrant up --provider=libvirt
Although I get the following Error and the vagrant box doesn't start up
==> default: Starting domain.
==> default: Domain launching with graphics connection settings...
==> default: -- Graphics Port: 5900
==> default: -- Graphics IP: 127.0.0.1
==> default: -- Graphics Password: Not defined
==> default: -- Graphics Websocket: 5700
==> default: Waiting for domain to get an IP address...
When I manually run sudo virt-viewer <domain_name> I get
Booting from hard Disk...
No active partition
NOTE: The box is available when I run sudo virsh list --all and the vagrant-libvirt virtual network is also active when I run sudo virsh net-list --all and it worked when I tried setting up a Alpine Linux box with Vagrant.