webcamd recently added support for v4l2loopback in FreeBSD (https://github.com/hselasky/webcamd/pull/9). It is now possible to create a v4l2loopback device:
# webcamd -c v4l2loopback
webcamd 74613 - - Creating /dev/video0
However, when OBS starts, it does not detect it and disables the virtual camera plugin:
warning: v4l2loopback not installed, virtual camera disabled
Expected behavior is that OBS would detect the presence of v4l2loopback (via webcamd) and enable the virtual camera if it is present.
There's already a patch for this that's been sent upstream:
Not sure I consider this fixed just yet.