During the last part of the year, for one of my FreeBSD machines i have had some kernel panics, like all of a sudden it would reboot. But since it was not often it happened, many many weeks apart.
I did not look more into it. I have also had read issues on the nvme drive, but again, it was such rare occations. I have a new nvme on the shelf, but have not replaced it.

Today a panic happened, and it did not come alive. I had run into this problem Zfs issue 13483

Seems scary that this 3 year old issue is not resolved.

I have most of it backed up, but i still felt that i needed to dump it on my NAS, so i in peace could sort out if i had something i had not backed up.
Don't think i have had a need to mount the fs from the live cd before. Have usually just reinstalled the few times i have screwed up something

Boot installer from a USB stick. Choose Live CD instead of Install
First i wanted to be able to login via ssh to remotely do changes.

  $ mkdir /tmp/etc
  $ mount_unionfs /tmp/etc /etc
  $ vi /etc/ssh/sshd_config
  Enable PermitRootLogin yes
  $ ifconfig re0 192.168.0.199 netmask 255.255.255.0
  $ /etc/rc.d/sshd onekeygen
  $ /etc/rc.d/sshd onestart
  

Then i tried to just mount the zfs pool, but it would panic again
After more searching, i found this

  $ mkdir /tmp/mnt && zpool import -R /tmp/mnt -o readonly=on zroot
  

Copying of the data as i write this. Still a heck of a scare.