Technically I guess what you'd do is hand type in binary code to create a hex editor, then bootstrap this forth off that, by hand-typing it in.
If you include formal verification tools as part of the stack then you can verify the tools by eye, type them in, and use them to verify the function of the stack.
Admittedly Forth is tricky to do here, but something like lisp/scheme/wat can actually be proven out with say microkanren.
From there we can trust the software stack.
