After a few hours of back and forth, I finally got more details from Google. Here's what this feature does, according to Google: "Long Press currently works in a select set of apps and system user interfaces such as the app Launcher, Photos, and Drive. This update accelerates the press to bring up more options faster. We also plan to expand its applications to more first party apps in the near future." Essentially, this new feature lets you press harder to bring up long-press menus faster. In fact, Google's documentation for Android's Deep Press API explicitly says it should never do a new thing, it should only be a faster way to execute a long press. The answer to why it only works in certain apps is that a lot of Android developers aren't using standard APIs for long press actions. Because Android. Okay, but how does it work? It turns out my hunch was correct: Google has figured out how to use machine learning algorithms to detect a firm press, something Apple had to use hardware for.
Read more of this story at Slashdot.