30 to 300GHz drill/vaporise rock haha good luck with 2 meters let alone 12 miles deep. After burning zillions of dollars they'll settle for 2000m deep right next to some traditional geothermal in iceland and be very opaque about what tech they used to make the hole.
Posts are replicated across any instances that are federating (think "following") your host instance so the metrics you seek are not possible without data from each server in the federation which could be ~40 servers currently. Its only a crucial point for sponsored content creators I think.
In terms of stats about the size/activity of the fediverse I think the most informative source currently is lemmymap here I'm very grateful for the insight it provides, but I suppose its far short of what you want.
Edit: some more graphical stats are available here