bhyve(8) is a hypervisor available on FreeBSD. I personally use vm-bhyve(8) to manage my virtual machines because I find it a bit easier.

pkg install vm-bhyve

You need dataset for virtual machines (if ZFS is being used).

zfs create zroot/bhyve

Update system configuration (rc.conf(5)).

sysrc vm_enable="YES"
sysrc vm_dir="zfs:zroot/bhyve"

Run vm init to finish initialisation. This will create subdirectories inside the dataset.

vm init

To enable network for the VMs create virtual switch and attach network interface to it.

vm switch create public
vm switch add public re0

Now you are ready to create Debian's VM. You can use sample config for this to make it easier.

cp /usr/local/share/examples/vm-bhyve/debian.conf /zroot/bhyve/.templates/

In my case I want to use debian template (-t) and specify disk image size (-s) to be 40G. The following command will create directory with config, disk image and log. This is a good moment to edit VM's config file and set things like RAM.

vm create -t debian -s 40G debian_vm

VM is now created but nothing is yet installed on it. Installation image is needed, it can be downloaded with vm iso (it will be placed inside /zroot/bhyve/.iso/).

vm iso https://cdimage.debian.org/debian-cd/current/amd64/iso-dvd/debian-12.9.0-amd64-DVD-1.iso

Install Debian on the VM.

vm install -f debian_vm debian-12.9.0-amd64-DVD-1.iso

After the installation VM is ready to be used.

vm start debian_vm
vm console debian_vm

vm(8) uses cu(1), to exit console back to the host use ~^D or ~.~.