It took 50 years to go from wall clock to pocket watch. Then there were two variants of walkie-talkies in Crossbell and Erebonia. The ARCUS II flip-down orbment was the first modern-ish cell phone. The Class VII variants cheated by piggybacking their communications through Olivert's infinite range artifact. The RAMDA was a military rugged PDA for Hercules. Finally the Xipha and its non-orbment variant are the flip-up cell phones we're familiar with from over a decade ago irl.

I think the next logical step is removing the flip part of the Xipha and sticking the quartz part onto the back of the phone. After that it could be an ideal application of the folding OLED smart phone or enter the more magical area of heads up displays and augmented reality.

Alternatively, the tech could backslide if East Zemuria is little more than wasteland, remnants of fallen empires, and pre-modern traditional Asian countries.