Amazon has their own app store - I guess the Fire OS is tweaked a little differently. I chose the Fire HD6 because it was cheap, pretty durable, had a decent rear camera, and ran gradecam, plicker, and a bunch of other apps I like to use in my practice as a classroom teacher.
Quick Key looks interesting but I can't use it with my fire. My nexus doesn't have a rear camera, and I do not like Apple products.
If you folks are interested in pursuing this, let me know and I will be more than happy to beta an Amazon flavor of the droid app. Frankly, it might just be getting Amazon to sign off on it - I understand the OS is not that much different under the hood.