Interesting turn this thread took.
Overt versus covert is always a consideration.
The kit that's cited by
@ddeuce22 obviously was not intended for covert use, but there are others out there that are specifically designed for covert wear, again to defeat a variety of threats from handgun to rifle.
The Bulletproofme.com website is probably among the oldest and best known resource for covert kit, however, many "cop shops" both local and online (i.e. Galls) will also sell to qualified civilians, either openly or via self-attestation, in much the same way that the overt tactical gear suppliers do.
I'm nowhere near as well versed in covert gear as I am in overt gear, simply because I don't really have a need for covert gear, and thus haven't played much in that side of the pool.
That said, typically the same set of compromises that's seen with overt armor also applies to covert armor - the threat matrix and weight/bulk and gear quality all interplay towards cost. The same caution should be paid towards NIJ certification versus "hobbyist/enthusiast vetted" protection, and this typically also is reflected in cost differences.
Personally, as a civilian who is non-military/LE/first-responder/security, even for a SHTF/TEOTWAWKI/WROL scenario, I do not think that overt armor will ever be what I choose to go with. Much like my view of open versus concealed carry, I feel that overtly displaying armor will likely create more limitations in terms of tactical considerations: specifically that in most scenarios, it has the potential to make me a more visible threat/target. In the same sentence, however, it should be noted that much of today's modern overt plate-carriers and armor all but disappear under the typical "athleisure wear" of a hoodie/sweater, windbreaker, or rain slick - and while these options may not necessarily be viable for everyday wear in warmer (or drier) climates, usual concealment efforts of simply throwing a larger, dark/patterned button-up shirt or T-shirt over the armor can considerably drop its visual profile, and this effect is compounded when visually distinctive wear such as recognizable work uniforms are worn. Although modern fashion favors a more fitted/tailored look, uniformed work clothes in particular have retained their typically "boxy" fit, and this can be used to one's favor, particularly if one is involved in delivery, utility, or similar work in less-desirable parts of town and/or at less-desirable times-of-day.
One could argue that for the vast majority of civilians that as soon as the long-gun comes out, whether or not we are also wearing overt armor will already be moot. Nevertheless, this statement in and of itself does not circumscribe set limits on the "why's" of the scenario. For example, if the home-defenders have already retreated to their safe-room and are safely behind defilade/barricade, taking the time to don additional PPE -be it armor or eye/ear-protection- is certainly a valid consideration, and one which may have additional payoff should the defender need to press the fight, regardless of how unlikely the latter.
For those of us who've come to armed self/home-defense, we are ostensibly already choosing to prepare for the unlikely worst, and to those who do not see things the way we do, the joke is always "what's the odds." Here, with armor, the math is the same - it's jut towards that next level of preparation. But here, of-course, also lies the truth that the hilarious 30-second skit that Chris Costa puts on at his classes, where he mimes getting kitted-up for a home-invasion scenario with a primary, secondary, and plate carrier - only to step outside the bedroom door and get shot in the head, because he'd forgotten his ballistic helmet.
The real question behind all of this is where do we each personally draw that line, and the only counterbalance is whether or not what we have decided to do actually plays well towards the scenarios that we've envisioned.
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A quick aside in terms of vehicle tactics and considerations for mass unrest, a ballistic blanket -although expensive and of limited threat matrix- is a viable consideration particularly for rear-cabin passengers. This, combined with a larger fire extinguisher, are two excellent pieces of defensive equipment to have, but with both, accessibility (i.e. "staging") as well as storage considerations should be worked-out before purchase.