As a cat owner, the big red button is kinda scary. Maybe 2 big red buttons on opposite sides of the desk...
I agree. As someone that bumps into things this could mean testing backups. My preference would be the internal door locks we used in the military. They are a metal finger guard that one puts their fingers into. There are 4 double-pole-double-throw momentary rocker switches with strong springs. The operator must know which way to simultaneously toggle each switch to activate. There is more to it than that sometimes a badge but for the self destruct I think that is all one might need. The finger-guard and the strong springs and having to know which way to toggle all four will protect against cats and children. I would also avoid anything proprietary. A 4 million volt stun gun activated until fully discharged is sufficient to destroy any circuitry. The stun gun connects to two rails on opposing sides of the SSD 2mm away from the board. A high voltage gas bulb in the chassis could provide confirmation of discharge.