Re: What if the SSD or Motherboard has failed?
"I refused to do this because it contained my digitial life."
Good. As already mentioned, this is another reason for drive encryption.
"but have no idea how to do so securely."
If your adversary is *not* KGB/NSA/MIx:
Get a hammer and punch or screwdriver.
If the drive is covered (SATA) pop the cover off.
Punch and crack the center of each chip.
For mechanical disks:
Same tools, but prefer something like a centerpunch. From the soft side (the thin stamped cover, not the cast chassis), punch one or two holes in the disk platters
https://en.wikipedia.org/wiki/Hard_disk_drive#/media/File:2019_Rozebrane_dyski_twarde.jpg
making sure you get as far in as the chassis.
No need to take the cover off, you can make out the structure from the outside
https://en.wikipedia.org/wiki/Hard_disk_drive#/media/File:Hard_drive_label_side.jpg
All drives have the same layout.