Android is "fine" for a general purpose tablet that you add apps to that has the Android GUI and VM. It's a lazy solution for dedicated eink ereader, a customised Linux is better. You need a custom GUI anyway for eink. Almost all apps and programs use the "scroll" model to show more content. The proper eink applications use paging. It's one thing the Kindle DXG web browser does better than any newer Kindle or Kobo browsers.
The Tolino may be fine, but I'd assume non-android is better. Certainly every TV I've ever seen with Android TV is worse than other Smart TV GUIs. The Andriod model has been badly ported to TVs. The only thing Android TV does better (sometimes) is installing and browsing Android Apps. Which I don't want on a TV.
Certainly the later Sony ereader I tested based on Android was inferior to the earlier Sony ereader without Android.
"The
disadvantage of Tolino is that Rakuten-Kobo was forced to Android when buying a Tolino, that all Kobo devices under the Tolino name are Android devices."
But maybe they are fine
Android uses the Linux Kernel and some Linux/GNU tools. The difference is the framework for Android apps (API to Google services and Android Services), the clone of the Java Virtual Machine to run the Applications, essentially written as if for Java. On a plain Linux you can use any tools or languages or libraries support by Compilers for ARM and Linux. Android, while technically open source, is Google controlled. Google approval requires also binding and distributing the closed Google "blob" needed for the PlayStore and other Google services.