Apple - trying to make it too easy
First off 'what version of EFI / SMC (might as well check both) firmware am I running?
Click the Apple icon (top left), About This Mac, System Report, Hardware (very top in left hand menu) look for Boot Rom Version, SMC Version. Not that hard....
And where, where are the current versions now that this article has 'raised awareness' ?
Apple has this deprecated article: https://support.apple.com/en-ph/HT201518
BUT apparently is bundling the updates automagically. So now we don't truly know. Very Strange apple.
Can one remotely (over a network ...say with ...nmap/nessus etc) determine the firmware version?
Notice the depth of information...systems over 8 yrs old are still supported. And largely function!