My old Kindle was perfect for this, small thumb-keyboard, great e-ink screen, amenable to homebrew.

Then an ex lost it reading Fifty Shades in an airport, and you can't buy them any more.

I'm saving up for a Remarkable.

If you're open to making it yourself, checkout /r/cyberdeck on reddit.

How do you know it's bad? It looks like it has a chance of being pretty usable.

The layout is just horrible. It would be a huge adjustment to go back and forth from an actual decent layout.

Not sure I would call it horrible, but when comparing with a TRS-80 model 100 keyboard then yes I would have preferred the layout of the latter.