Can someone explain to me how most of these inexpensive Chinese smart watches work?

Can someone explain to me how most of these inexpensive Chinese smart watches work? I am familiar with android wear. There are many apps available and many ways to customize your watch with android wear.
I know the app selection on the cheap Chinese watches will not be as large as something running Android wear, but I’m not too worried about that.
My main concern is having a good looking watch that is customizable. The only “smart” functionality it needs to have is alert me of texts or emails or phone calls.
I am also on the watchmaker forum a lot. I love the creative watch faces that people make but I’m not sure if they can be transfered to these watches or not.
The watch I’m looking at now is the mlais watch. It’s the design closest to the Huawei watch I’m looking for. It is finally available but I don’t know if it is worth it. If I can’t customize it, I might as well buy a regular watch with one face.
There isn’t much hype about the mlais nor have I seen many people that have one yet.

Think at all things you can’t do without you smartphone connected or a free WiFi…NOW you Can!!!

That’s not really what I was getting at. Being free from my smartphone is nice, but I don’t mind being tethered to my phone. I’m more worried about making customizations (watchfaces and straps).

All these watches are following basically the same concept:

A housing with lot of cables connected to the strap. You can’t modify them unless you are VERY good at electronics, because you have to find a good place for gsm/bt/wlan antenna.

The other side is the software which is a fully working Android 4.4 or 5.1. Tethering to your smartphones does not work reliable.

So if you are looking for a companion, stick with Android Wear. If your are looking for a Smartphone on your wrist, use these watches.

@Vmax thanks Dirk. I would only try to change a watche’s straps if they were interchangeable. That’s why I was trying to stay away from the ones with antennas in the straps. If I like the straps that come with it, I might reconsider, but I like to switch between silicone, metal, and sometimes leather.
So Bluetooth tethering is unstable on most of these watches? If I die get a standalone watch, would my service provider charge me per month for an extra sim card?