Similarly Psion has a pretty nice device. The psion 5 had a nice keyboard and limiting OS. It supports apps/app stores, but required windows and memberships to be a developer. I pushed them to open up a bit to get more apps, they thought it was a bad idea.
Speaking of which, there is a modern incarnation of that form factor in the shape of the Cosmo Communicator (and it's 1st gen predecessor, the Gemini PDA):
(I have both. Runs Android; desktop Linux port is promised: Sailfish also landed on the Gemini. If you want a modernized Psion 5 this is the biz, although caveat emptor: it's from a very small company and has rough edges on the software side.)
As for the Psion 5, its descendants only recently went away: Symbian (in all its flavours) was developed from the EPOC/32 operating system that it ran, after Psion hit the buffers and Symbian was spun out.
