Earlier quoted context omitted.
> guess the contents of a box Use X-ray? or whatever can penetrate the exterior shell
All big and security-responsible companies issue their employees special phones and laptops when they go on business trips to countries like China or Russia and these are quarantined immediately after they return. They get wiped, X-rayed, disassembled and checked, including any accessory (chargers, mice, etc.). The more critical the field, the more you have to treat those devices as untrusted before attaching them to…
Given how sophisticated these attacks can be, I'd think they'd issue disposable equipment to be destroyed on return, like a cheap netbook or something. I don't see how you could trust an individual viewing a simple X-ray scan to detect some extra microchip the size of a signal conditioning coupler.