I am surprised it does not mention Psion. With better management we could had iphone 10 years earlier. Psion Series 5 has no replacement even after 19 years (keyboard, display, battery life..)
I'd say most netbooks or tablets replaced it for all of those things now... But you're right that Psion were super innovative. More important than their series 5 hardware was the operating system. EPOC was a 32bit embedded OS long before anyone else was doing them. It was nice to program for and dealt with multiprogram which even the first iPhones didn't think about.
32-bit EPOC became very popular (for a while) as Symbian, but the "nice to program for" aspect was definitely lost in Symbian's heavy-handed multi-vendor committee approach to software design.