This item turned up for me on my return from the USA late 2018: The K2 OLED Bluetooth Smartwatch. This is an updated version (June 2019) of the original December 2018 blog entry as I just successfully updated the app and watch firmware.
The watch has magnetic charging and an App for iPhone and Android – I used the Android version called “iband”. The app is referred to in the 12-sided booklet that comes with this inexpensive watch and it all works well. I had no difficulties at all pairing the watch to my Pocophone F1 smartphone, a process which thanks to the use of a QR-code took moments only. Unlike some other smart-watches out there which die after a day or two even if not used, the stand-by time of this watch is very long.