There are a few writing appliances out there trying to do that, but they are all based on proprietary solutions. It _might_ be possible to get a decent e-ink display with a passable refresh rate at non-monopolistic prices and bypass the Rube Goldberg-esque setup by just plugging that into a Pi via SPI, but right now there just aren't many options for that out there.

Remarkable 2 with folio case gets close!

I don’t have the Folio case, but I have a Remarkable 2 and the screen refresh time is not as nice as the Paperwhite by quite a margin. I had actually managed to plug a USB keyboard to the RM2 (can be done, you need to tweak several things and power it) and the experience was quite “meh”. Also on a personal note, I prefer the form factor/size of the Kindle for this. The RM2 always feels flimsy!

That seems strange. You can use the pen on it, and the screen changes near instantly. There is not much of a lag. I would think that typing would be almost as good.

Edit: I see this guy typing here, and the latency doesn't seem horrible. Probably equivalent to the latency of an actual mechanical typewriter. https://youtu.be/R8VG6dQkTwI?si=_YWK7-fLw7MhS1Vv&t=2226

Of course, this folio keyboard looks horrible.

Writing latency on the RM is good: for typing is very likely to be well above OK… as long as you don't have to scroll the text/screen. Because page turning latency/refresh speed is quite bad. No "this is shitty bad, gimme my money back" but slow enough that it makes skimming impossible and normal page turning slightly annoying (worsened the larger the PDF). A similar kind of latency can be seen particularly when using the cut/move tool, for example.

To be fair when typing (a few minutes after the time in the video you shared) the latency for refreshing the screen does not seem that bad. But they keyboard looks annoying to use… I way prefer having a full choice of keyboards (aside from the fun of having written the code of course).

Typing latency on my contraption is pretty similar to what can be seen in the video, maybe slightly slower but not by much. Since two weeks ago I have written several drafts of blog posts (while I added some features that were needed, or fixed some annoyances) and it is usable, although I miss adding a "read mode" (scrolling via cursor is slow, and I have not added `:num`, `gg` or `G` yet which makes reading what you have written not great.

This has no OS (at least that you can access). I have one, have written a number of drafts with it, and regret both purchasing it and it not being a better machine. The software is really bad and there is no way to tinker with it, no way to write custom software. Indeed, in the last update before it became abandonware, they made updates cryptographically signed to make it more difficult for people to jailbreak it. The hardware is pretty and the keyboard is nice but the battery is really bad. It lasts only a few hours and takes forever to charge. And if the battery is depleted, it takes too long to get to the charge level necessary for using it even while plugged. Please don't buy this.

The screen and battery are too small; you really want a laptop or subnotebook form factor where the screen opens like a book so screen and keyboard can both be large enough to be useful.

A5 format (like a book, slightly less than most laptops) seems a sweet spot, also for keeping it in a larger jacket pocket.

I have one of these sitting next to me right now, and it's essentially unusable due to the dispaly lag, and largely (though not completely) reliant on a service from the vendor for syncing. The hardware is passable, but the software is not, and it seems to be at a very slow drip of maintenance, if not completely abandoned.

Boox Tab Ultra?

https://shop.boox.com/products/tab

Nice, and the price is okay, but the keyboard is not suitable for longer writing sessions.

Even its very own demo video shows a lady on a software with the device AND her laptop (how ironic)!

If anyone has it, how long does the battery last?

I don't have that one, but I have one of the A4 sized onyx tablets. I use it for sheet music, turning pages with an air turn pedal

I get about 3-4 weeks on a charge, albeit with somewhat light use

These are good but lack the OS.

I want Linux and/or ssh

The Boox Tab runs Android.

I don't have one, but I use the Android app Termux on my stock Kindle Fire tablet. It's a rather complete Linux on Android. Not emulation.

CLI environment just works, and I've been able to run GUI apps with some configuration and an additional Android app for X or RDP or VNC. I generally don't use a Bluetooth keyboard or mouse with my setup, and I tend to avoid the GUI stuff.

But for extended shell scripting or writing CLI Python C code all native, all local, no networking needed. And I use it all the time for SSH.

https://termux.dev/en/

I've set up a Kindle that can ssh into my NUC with attached keyboard with a few taps of the screen. Is that close enough?