Pardon the naive question...

Verifying checksums with the package is useful after filesystems somehow got damaged. It's not useful as a way to detect ownage. Querying the box itself for ownage is pointless. "Nothing to see here, pinky promise!"

Flatten and rebuild is better and even that might not be enough when the box itself can reprogram an eeprom. This is why hardware freedom has become at least as important as software freedom. Easier to audit, inspect and generally reason with.