The Human Interface Guidelines for Live Activities provide several examples of compact presentations that have a timer counting down formatted like "3min" or "3m", similar to the timers in the Clock app. Such examples can be found in this Stack Overflow question: https://stackoverflow.com/questions/77551496/is-it-possible-to-make-an-only-minutes-1m-countdown-in-a-live-activity
A Timer initialized with init(timerInterval:pauseTime:countsDown:showsHours:) has provided a live countdown timer in widgets and live activities, but the formatting is limited. And since live activities come with limitations that prevent us from using Timers, there's no real way to implement this kind of thing ourselves.
What is Apple's official guidance for implementing this kind of timer for the compact presentation?
