[tomsem]

A quibble about Dark Mode:

Kobo Clara Colour and Kindle Colorsoft Signature Edition do not have system wide Dark Mode, it is a reading setting only. User Interface elements retain white background. Maybe this deserves an asterisk.

Kobo Clara Colour does have Invert Screen option (if you enable Developer options), which requires restart to enable and disable, and is not very discoverable. Moreover, it is incompatible with color content: it inverts colors as well and the toggling the reading Dark Mode will not invert the color inversion. So to me it does not qualify as Dark mode.

PocketBook InkPad Color 3 only has System dark mode, which can be toggle in quick settings in any context. Unfortunately like Kobo's hidden invert screen option. it inverts colors so is unusable with color content. Maybe that's a double asterisk Dark Mode.

There must be some underlying reason why it is problematic with Kalaeido 3 to avoid the compromises that all of the above have.

I do not use Dark Mode on any of my e-Ink devices any more, it is just a better reading experience to keep some lights on. But to me it is or would be annoying to read in near total darkness and get blasted with light just changing a font or to select another book.