I agree that the technology already exists for a secure election. What is missing is the backbone / will in the state legislatures to implement a secure voting system.
A few minor changes to this specific proposal:
Pins must be 8 characters
Voter rolls are locked the day after the new president is inaugurated and all voters must re-register.
No mail in ballots without a signed request for a ballot and a legal (ie under penalty of perjury) statement claiming a voting disability (out of the country, shut in, military service, etc.)
Those are all helpful things. I would add that only open-source voting software would be allowed. That would provide an army of people examining the code for vulnerabilities and back doors such as being able to modify logs, delete log entries, and hide your tracks.
But those fixes do not address the problem that the equipment is attached to a printer and that printer cable can be used to attach nefarious tools like the Bash Bunny.