You cannot formally verify heat-induced transistor stability issues, solar radiation, next-cell state change caused by EMF from adjacent cells (rowhammer)....

And while possible, good luck validating systems against intentional attacks-- fault injection, power tampering, bus attacks....

It is vital that "formally verified within X scope" does not turn into the leaky abstraction "is secure". Go watch Microsoft's talk on XBox security, and what they had to do to make it as secure as it is (primarily: tightly control hardware, code, and platform). It is not something you throw AI at, and it's not something that you can generalize to the entire computing world.