I've used FreeBSD install media to recover too. You can get a shell and there's no need to download other stuff. I haven't done this to recover ZFS as written

I've used FreeBSD install media to recover too. You can get a shell and there's no need to download other stuff. I haven't done this to recover ZFS as written by Linux or Solaris/illumos, not sure how well that works but wouldn't be surprised if it does.