I don't know if they are the best option, but Kobo stands out in terms of being a practical reader and being hackable.
A nice feature on most models prior to the Clara HD is an internal uSD card. (This is different from the externally accessible uSD slot found on some models.) Pop open the case, remove the card, make an image, and you can be assured of restoring it to a working state without any fancy tools. With the uSD card in a computer, you can examine it and modify it. The models that I have cracked open also have a place to add a header for a serial connection, though I haven't tried using it.
Kobo does not appear to have any interest in locking down their devices. Software updates are shipped as zip compressed files wrapping a gzipped tarball. That tarball is simply a directory tree containing files to add or replace. Many third-party modifications are distributed in this manner and you can do your own modifications without ever cracking the case open. (Though I do suggest opening it up and making a backup before modifying it.) As far as I know, there is no protection on the proprietary software components and Kobo hasn't said anything about third-party patches. This has been the case for nearly a decade now, which is why I lean more heavily on the word modifications rather than hacks. Most of what can be done relies upon an developer's knowledge of Linux.
There are also various projects that you can learn from. Some provide tools to make developing software for the Kobo easier, while you can examine others to figure out how to setup a toolchain. I have seen C, Rust, Lua, and Python based projects for Kobo readers.
The Kobo development forum on the Mobileread forums is the place to check out for more in depth information.
I presume that the internal sd card would help the longevity of the device as well. Like someone mentioned, they upgraded their storage. You could do the same thing, if after say 5-7 years, the card starts degrading and the reader starts slowing down.
Post author here. I'd still recommend going over to the MobilRead forums; and picking up an older Kobo device (like the Aura HD ^_^). They don't even need any user registration (https://www.mobileread.com/forums/showthread.php?t=223155). There are full firmware dumps, and its super easy to modify. There are even some examples of running full blown Linux on them (https://www.mobileread.com/forums/showthread.php?t=220350). Plus you can bypass Nickel and stick to something really nice like Koreader for reading; or Plato or CoolReader.
I've always used Kobo e-readers because they show up as storage over USB and then you copy epub files to them and they automatically pick them up, no jailbreak required.
I don't know what's involved with trying to do the same thing with Kindles, and I don't know about hacking the firmware.
I have a recent generation Kindle Paperwhite, and you don't have to do anything special to "side-load" ebooks onto it. As long as they're in a compatible format, you just copy them into a specific directory -- IIRC it's something like /documents/Downloads -- and they'll show up on the device once it's disconnected from your computer.
Correct -- EPUB is still not supported, and IMO, is a very deliberate exclusion. MOBI is still supported, which was always funny to me... until I looked it up again just now and found out that Amazon bought the parent company way back, so that makes more sense actually.
> I've always used Kobo e-readers because they show up as storage over USB and then you copy epub files to them and they automatically pick them up, no jailbreak required.
> I don't know what's involved with trying to do the same thing with Kindles
Kindles behave in the exact manner you just described. There is no difference. (Well, the Kindle won't read an .epub. They read .mobi instead.)
People have been developing apps and alternative shells for the Kobo for a long time. It's a bit more involved than the Remarkable but nothing close to jailbreaking a walled garden device.
I was considering getting Remarkable 2 when I am in a country they deliver to. Do you know whether it preserves the qualities of Remarkable 1 you mentioned, apart from the price?
The software running on both devices is identical. The main difference from my understanding is that the battery life is better on the RM2, and then pen has an eraser on the back.
I've heard mixed results about writing quality, from my reading most people have said writing on the RM1 "feels" better.
They would not make good e-readers. They're interesting, but the use case is more like a display device than a complete system. For example, development involves the arduino ide, while other e-readers run linux and full-blown applications.
Recently bought the Boox Nova3 and in terms of being hackable it's pretty good. It runs android so you can install anything from the app store. Runs chrome pretty well on the slight ghosting setting. I returned it for the kindle because I couldn't really see my self using it over my phone for browsing and anything I want to read long form I can get there. If you want to go all in on e-ink though I'd recommend it.
It's worth noting that Onyx actively violates the Linux kernel's license by refusing to release the source code. This hampered my hacking efforts as I was trying to build AOSP for the device.
For something cheap (20-30$) a lot of the older Kindles are pretty interesting (and modern enough after updating OpenSSL for TLS 1.3). After "jailbreaking" you're left with a pretty normal Linux from 2012: X server, awesome WM, dbus, upstart with commented shell scripts.
