Maybe it was U1? There are too many apple chips that it is easy to confuse now.

I can't find anything on the page saying exactly which chip it is. Regardless it was a chip that was missing from the original but is in the Mini that made this feature work.

That would be awesome, I would love some feature that it could actually be room aware and knowing where devices are in that space instead of just relative to your phone when searching for an AirTag.

But I imagine that would likely require a workflow of mapping your space with your phone first.