According to the github issue it seems to be a simple checksum step, not a true signature verification? If so there is no locked bootloader in any real sense.

If the real impediment is lack of demand or low-level development effort for any given device, that's in principle a solvable issue once projects like pmOS and Mobian choose to focus on some reasonably-available hackable hardware and bring it up to true daily driver state.

Can you just access /dev/mem or load a kernel module? Is there a SELinux policy stopping that?

If you can do either of those, it should be trivial to get kexec working by just loading it as a module.

Older Kobos sound ok though?

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.)

Also consider koreader instead of the stock reader app.

Most (?) Kobos can run libby so you can get ebooks from your library.

I use the Calibre support, but did not know you could install additional software that easily!

Android on an e-reader unlocks so much potential. I've owned four or five Kindles over the years but recently switched to an Onyx Boox page 7" as my main e-reader. Expensive (relative to Kindles) but runs full Android 11 and has physical page turn buttons. I use an app called BookFusion to sync my library including reading position across all platforms. Battery life isn't Kindle grade but I can get by charging once a week which is a good enough tradeoff for the convenience of being able to run Android apps.