IoT devices will typically only have a few kB of RAM, so yes, it does matter. As a data point, I'm working with an ARM Cortex-M0 processor at the moment and it has a grand total of 128kB program memory (flash, so you can't use it for read/write data storage) and 16kB RAM. This is an entirely typical processor for this sort of IoT application.

Sounds like the Psion 7: http://newth.net/psion7/index.html

Excellent keyboard, colour screen, runs for ages on a charge, fast and lightweight EPOC operating system. Now discontinued. :-(