When listening to an ebook it is easy to fall asleep, either on purpose or by accident.

I suggest monitoring awake/asleep state and pausing the ebook reader.

Monitoring could be done through one of those smart watches that all seem to create graphs of how long you have run and for how long you have slept. It could also be done through listening to breaths or watching eye movemements.

The ebook reader could be paused or a book mark could be set.

There are many ebook readers, several for every device.  But no one can synchronise my reading between the devices.  (i.e. none that I know of)

What I want is to read my book in bed on ebook reader hardware.  Then, while commuting, I pick up my phone and continue reading where I left off.  Back in my sofa at home I read on my tablet or TV.  Not to mention to be able to read at the computer.

I suggest skipping creating an app for every device but instead make it online.  I mean… what can’t be solved by HTML5 nowadays?

There is a solution, Ibisreader, which already today keeps some of my ebooks.  I can read my book at every web browser be it computer or phone.

What it lacks though is a better user interface and above all a better way to track where I am in the book.  It uses some kind of chapters? and they can span several screen heights.  I would like to have the browser know which page, screen wise – not paper page wise, I am on so it can open the right page when I continue reading on the next device.
There won’t be an exact match when moving from a bigger screen to a smaller, say a tablet to a phone, but unless I have a very big tablet with a very small font it won’t be far off; and probably not even then.

Ibisreader is F/OSS so I guess it would be a good place to start.  It could also be a nice way to learn Html5.