+1 to a Kobo, they cheaper and better than Kindles, with full Calibre support (https://github.com/kovidgoyal/calibre - OSS which has been in development for ~20 years!).
The way you install additional software is literally just moving files into folders whilst its plugged into your computer. I'm sure it could handle Tailscale.
I agree with your sentiment that the Kobo is better than the Kindle from an... ethical standpoint, if you have the money for one. However, it is worth noting that Kindles will always be cheaper than Kobo devices [0] due to economies of scale and lockscreen advertisements (removable with jailbreaking). From a pure cost perspective, and assuming the user is technically-minded enough to accomplish the jailbreak, the Kindle is likely always [1] a better deal.
[0] as of today, 12/8/25, the "base model" Kindle 11th Generation is priced at $109.99 USD, and the respective Kobo Clara BW is $139.99 USD.
[1] I say "likely always" to cover my bases. To my knowledge Calibre supports Kindle, just not as well as Kobo. That said I have found that the KOreader app is more than powerful enough for my use case (reading my own epubs, using dictionaries, etc.)
The current colour kindles and kobos don't use real eink colour. It's just a bw screen with lcd colour overlay (eink kaleido)
The real colour screens are used on the remarkable (eink gallery) and they are indeed slow for full page updates though remarkable seems to have done a lot of smarts for local updates while drawing.
Where do I get DRM-free ebooks to put on a Kobo? I don't support breaking DRM. So I'm using a Kindle because it has the best access to and integration with almost any book I want.
I kinda love that buried in the koreader menu somewhere is an option that drops me at a linux shell. I have no use really for this feature, but i like it. Good for those times you absolutely have to crank out some awk on the plane or whatever. :)
But what I'd really like is an option not to hide the navigation bar while KOReader is open. I work with technical PDFs and need to jump between applications very often.
The way you install additional software is literally just moving files into folders whilst its plugged into your computer. I'm sure it could handle Tailscale.