There are a lot of things you could try that would make it much more difficult for a competent data recovery specialist to recover your files.

If your gas furnace with a circuit board stopped working, would you take it apart, asking questions on Reddit about how to find it?

I have no relationship with www.myharddrivedied.com except as a happy customer (an SD card failed onsite before I could back up important photos).

Go with the experts.

I don’t believe there are valid arguments for failing to trust AES 256 encryption in an open source implementation that has aged well. For your situation use Veracrypt virtual drives. Unmount the drives remotely. Done.