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Nearly 500 smartphone brands have left the market since 2017
(www.techspot.com)
This is a most excellent place for technology news and articles.
That was the Motorola Moto Z series for ya, had pins on the back for modules to be attached. Some modules were a battery pack, jbl speaker, a projector, and even a little printer to have the phone work like a polaroid
I was just wiping my Force 2 the other day to install an unlocked OS and was impressed how much battery life that clip on pack gives it.
Without it the Force 2 was the slimmest phone on the market and with the pack on it just feels normal. Yet I can get like three days out of it, and I bought it in 2017.
Also the LGG5 to a lesser extent. I had a chin module that acted as an extra battery and fine control for the camera.