The iPhone 12 "smart connector" may actually be a heat sink exit using composite materials in the mid-frame and a composite outside frame. See the photos below. (The smart-connector idea was just a guess from Joshua's video (see below), and in fact is much smaller than the actual smart connector found on the most recent iPad. The area in question is the small pink oval found in the last photo. Compare it to Figure 6A in the first photo. Same location.)
The first image below is from an Apple patent for a heat-transferring composite mid frame.
The images of the battery layout and "smart connector area" are screenshots of the video posted by Joshua yesterday (see below).
Finally, recall Gamesc's recent Apple patent post (157252210), in which the first point of the patent is this:
So, the worst-case scenario appears to be that only a tiny part of the mid-frame and a tiny dot of the external frame are liquidmetal. Best case, the entire external frame and most of the mid-frame are liquidmetal except for an even-more conductive heat-transferring metal.