Feh. Well, to heck with that.
A few years ago when Apple came out with the 6th-generation iPod Nano (the little square one with the touchscreen), there was a modest aftermarket in watch straps. From what I've heard, it actually made a pretty decent wristwatch, without having to be tied to a phone. Should have bought one when I had the chance.
I hate to have to break this to you, but the reason it doesn’t work without the iPhone is because it does tens of things in conjunction with the iPhone that makes it so you don’t have to pull the phone out of your pocket.
That’s a good thing. If you don’t have an iPhone, you wouldn’t want this anyway. Many of us who do, will.