There is also a rust book that walks through building a todo app with rust and gtk (gnome desktop). Haven’t gone through it yet myself, but might be something you’d be interested in skimming through.

There are watches that have an actual 24hr face as you describe the normal 6 position is 12 and 12 becomes 24. Which I think are fairly uncommon, I don’t recall ever seeing one in person.

More common to just see analog watches with dual time markings say a 24 under the 12.

An image search along the lines of “24hr watch face” will show some examples.