Take a look at HOWTO: Debian Installation on FreNAS (bhyve) I wrote a while back but should work on FreeBSD, FreeNAS runs on OpenBSD or FreeBSD, can’t remember which.
Take a look at HOWTO: Debian Installation on FreNAS (bhyve) I wrote a while back but should work on FreeBSD, FreeNAS runs on OpenBSD or FreeBSD, can’t remember which.