Start up / boot up time: slow because of Android?

Kindles start up in pretty much no time: you turn them on and they're ready for use.

How about the Onyx/Boox readers? Is start up slow because there's an Android system to boot?
Is it not much of a deal because you can leave them in standby without draining too much battery?

Are startup times comparable on all Android-based ereaders, or are some better?

I haven't managed to find any reference to startup times on this forum; only one review on another site mentioned a boot up time of almost one minute on a 10'' device (I'd be looking at 6'' readers, but I doubt that makes much of a difference).