>>107303920
If you want a 1:1 clone of the disk, probably the best way would be lsblk
dd if=[dev/sdX] |tar [options you want] |[compression you want, zip/xz are decent for >>HDDs, lz4 is faster] [location you want]
OR dd if=[dev/sdX] of=[path/to/folder/image.iso[if you want it as file and not overwrite the disk, otherwise /dev/sdX]]
NVMEs will be nvmeXnYpZ
If you want specific partitions for sd it will be sda3 for the 3rd partition of the first "disk"
You can use timeshift/similar to get all but the bootloader and/or root
The disk image is not efficient to create though