In this case there is only one Linux filesystem - it is fair to say this is the important partition with relation to Manjaro.
Proceed to create two temporary mount points in the live user home
Mount the partition nvme0n1p8 temporarily
sudo mount /dev/nvme0n1p8 ~/root
Attach your external disk and repeat above command to identify the external disk
When you have identified the external disk - mount the disk’s storage partition e.g. /dev/sdy1 - ensure there is enough space to hold your uncompressed data.
sudo mount /dev/sdy1 ~/usb
Create a folder to hold your backup the**
$(date +"%Y%m%d%H%M")** will be a timestamp
Create a variable with a timestamp
Create the backup folder
Use rsync -a to backup /etc to the storage device (files readable only by root will only be copied if run as root).
The -a flag stands for “archive” and syncs recursively and preserves symbolic links, special and device files, modification times, group, owner, and permissions.
rsync -a ~/root/etc ~/usb/backup-$timestamp
List the content of the root/home to identify the username e.g. fido
$ ls ~/root/home
Use rsync to backup the home folder e.g. fido
rsync -a ~/root/fido ~/usb/backup-$timestamp
Verify the content of your backup - and when satisfied - do what you gotta do.