Even tiny sensitivity would be better than nothing – or something that's so slow & expensive it's impractical.

But other antigen tests purport to have 90%+ sensitivity.

And the kinds of "PCR positives" they miss are often cases that are no longer infectious, anyway: lingering viral fragments, rather than live full-virus shedding.

So: ideal for border-control & creating other internal gradients that help suppress the worst active cases. The perfect should not be the enemy of the very good.