The instructions were tested on a Lenovo X1 Carbon 5th Gen (X1C5) on Arch Linux but should be applicable to other Lenovo models and Linux distributions.
BACKUP YOUR DATA! I created a bootable Ubuntu Image like this:
$ sudo sh -c 'curl --location --silent --fail "http://releases.ubuntu.com/18.04/ubuntu-18.04.1-desktop-amd64.iso" | pv > /dev/<your-usb-drive>' # note that pv is only there to show progress, it is perfectly fine to redirect curl to the usb drive directly.
then I booted from this drive by pressing F12 on reboot and dumped my NVMe disk to an external hard drive like this: