A few retro gaming handhelds for 80er on the market, as of 09/2019.
Building a retro game console with Raspberry Pi 3A+, Waveshare Game HAT, and RetroPie.
Palm and Psion (EPOC) are still my favourite tools today, although they are quite different: Palm is purely single-tasking, while Psion is real multi-tasking. Although they are both around 20 years old, there are still resources on the web.
The Psion 5MX has a comfortable keyboard, a clear screen, a pocket size, a good system, but incapbability to communicate with moden devices.