The parallels don’t quite line up, as in this case, they could be issued official cables that have a condom integrated/soldered on. Maybe in a special colour to

The parallels don’t quite line up, as in this case, they could be issued official cables that have a condom integrated/soldered on. Maybe in a special colour to remind you that these are “secure” cables. It’d be like your internal corporate email client not even letting you send mail out to external addresses. Sure, you could intentionally set up IMAP with an untrusted client and then send such messages (and likewise, you could intentionally bring some other insecure cable with you); but someone doing that would likely have a visible pattern of doing that, long before they actually get spearphished—one that could be noticed and reprimanded. Of course, ideally, you’d make using the insecure clients / cables impossible, by giving the “other end” a proprietary shape that only the secure client/cable fits with. (Maybe they could design a little adapter that could be semi-permanently socketed into a phone’s USB-C/Lightning port, turning it into something proprietary that only their secure cable has the male end for? I’m assuming here they still need a data connection — with a different special cable — for device maintenance; otherwise you could just make that little socketed-on adapter be the condom.)