Many Android E-ink tablets (like my Onyx Boox tablet) have these page turn buttons which are secretly the volume buttons and appear as such to most apps. Lots of reading apps (e.g. Kindle) support using the volume buttons to turn pages. It would be great to have a “Use volume buttons to turn pages” setting in the Android app to make it friendly for this use case.
This might relate to / solve PageUp/DOWN on e-paper reader (Onyx).