[Fnoord]

You can use a Kobo offline, see this guide [1]. A Kobo runs Linux under the hood, IIRC Android (probably some old version which is why I keep my WLAN offline and only allow on guest network. This also helps with battery). You can also install custom applications on it, for example Cool Reader [2].

A ReMarkable you can just SSH into. Which seems far more friendlier for customization, but its also a different price class and purpose.

[1] https://kobo-offline.virgulilla.com/

[2] https://www.mobileread.com/forums/showthread.php?t=222803

[scottlocklin]

what? nobody mentioning Koreader? Light years ahead of whatever Nickel reader comes with the thing.

[Fnoord]

Link [1]

Sorry, I never used any custom firmware on our Kobos. You see, I keep them offline, so I'd care less about security vulnerabilities in them (plus if they go online, its via guest network). Also, I am very content with the software on our Kobo readers (Aura One and Aura Two). I do use Calibre + USB sometimes. What am I missing out on?

[1] https://github.com/koreader/koreader

[scottlocklin]

Stuff I use every day: column reflow, djvu/chm/mobi support, cropping and zoom on text size even in scanned images.

Supposedly lots of other features as well , but simply supporting djvu is so huge for me, I can't imagine bothering with nickel.