The Beepberry and Pocket CHIP are not unlike these, though they have a portrait form factor and a more raw aesthetic. Small, wide LCDs can be had; it's tiny keyboards that are hard to get. I'll add that I don't value tiny keyboards much: it was a netbook keyboard that first made my wrists hurt, and since that time, I need my keyboard to fit my hands far more urgently than to fit in my pocket.
Earlier than these, I have an HP 95LX: a handheld equivalent to a PC-XT, with a 40x16 character mono LCD and one megabyte of battery-backed RAM, with DOS and Lotus 1-2-3 in ROM. The keyboard is made of HP calculator keys, which were often lauded. It would be somewhat promising for a mod, except it's vintage enough that hacking it up would be a shame.
Awesome! The only other keyboard I've seen this on is the Ergowarp. I couldn't quite manage to tweak it properly, and I have so many nice-to-have requirements floating around in my head that I can't progress with a design. Well done!