DX is the DXG with inferior screen.
Also most places the 2G/3G no longer works. No WiFi. Without JB and USB Networking you can't set the date/time and then it's 1970 and all is broken, unless you get a cell connection (and can take a day).
Certs out of date so web browser doesn't really work.
Never post entire serial number as people could perhaps get it blacklisted.
I think Duokan might not work well on the K1, K2, DXG and DX (not enough RAM).
I suspect minimum is a K3 (though DXG was released just after K3, it's basically a DX with better screen).
https://wiki.mobileread.com/wiki/Duokan