So I've picked up a Palm Pilot used on eBay. So far I've used it for some todo list type stuff and installed a few games. Using an offline device is novel, too. This post was written in the native memo app using Graffiti2.
I love the idea of Graffiti, even if in practice it's kind of a pain in the ass!
On the DIY pda front, I am still waiting on hardware but I have started on a basic notepad application in an emulator. Reading into the LILYGO T4 and M5Paper development kits more, those are VERY tempting as an all in one option. For the time being I guess I'll persist with my cheap janky gear until I'm sure I know what I want to achieve!