OK, to be clear, you can boot to raspbian or your distro of choice and use hdparm if you have a proper SATA controller and connection. This does not work on NVME drives.

#shred

If you have a spinning disk and either are forced to use a USB to SATA adapter or if the drive itself does not support secure erase, then you can use the shred command.

shred -fv /dev/sdb

will write random data to the sata device sdb. f is for force and v is for verbose. You can add z to add an extra zero pass and z to change the number of passes. That means that

shred -z -n 5 /dev/sdb

should do 5 passes and then zero on drive sdb

It will ALSO work for older parallel drives that identify as hd or that still appear as sd with a USB adapter. You had better check your devices with a lsblk before you run it. It will probably overwrite the OS of a running system.

Last word on shred is that it is ungodly slow. One pass of 1 tb takes 1.5 to 3 hours.

#hdparm

For SATA drives that support it, you can use hdparm. A deep explanation of what I’m doing is available here: https://grok.lsu.edu/article.aspx?articleid=16716. I could write out how to do it, but it goes into greater detail.

For forcing the system to sleep, you may need to

echo disk | sudo tee /sys/power/state

Also, be sure to set a password when prompted. If you omit the password, you may brick the drive. I have rarely been able to unbrick a drive.

This process may take several hours. The output of hdparm -I (that is an uppercase i) should tell you how long.

#NVME

Check processes here: https://wiki.archlinux.org/title/Solid_state_drive/Memory_cell_clearing#NVMe_drive

I have followed them once upon a time, but i haven’t done it in years and cannot offer solid advice.