Sound like we'll all need more things like this eventually :(
In practice, most people can conduct a reasonable verification through a series of challenge/response interactions based on shared knowledge, should they need to do so. Mentioning something done, said, or shared in private recently would suffice in many instances.
For more robust tradecraft, should you need it, a set of one-time codes (passwords or passphrases) might substitute.
When the former head of InterPol was arrested in China, he managed to alert his wife through the use of a duress signal, an image of a knife:
Not subtle, but effective.
In the film Capricorn One (1978), one of the astronauts alerted his wife by referring to a holiday they'd recently taken together, by mis-stating the destination as Disneyland, rather than Hollywood -- the land of make believe -- as it had actually been, which led to the revealing of the hoax mission.
If I'm being coerced, I could have a codeword to indicate that. If I'm being spoofed with AI, I'm not in control of "my" words, so I can't. I need instead to prove when I'm not being spoofed with AI. That's the purpose of this second codeword.
All my loved ones are on my iCloud so I would just ping their phone/watch while confirming location and asking the assailant to let you hear the phone ping on the line.
Also, you are lacking in the abstract thought department. Get that fixed, for your own benefit.
You don't because it statistically never happens. Just like you don't prepare for a plane crash or a lightning bolt striking you.