Can I get Fire OS 6 running on a Fire HD 10(7th gen)? Android Studio claims Fire OS 5.3.6.4 is Android 5.1.1 API 22.

I would really like to be using Nougat (which apparently Fire OS 6 is).
Shouldn't I have the latest Fire OS on my tablet?

Is there a way to do that?
If not, I'll have to try rooting it. I hate these OEM blonked Android OS flavours!
Fire OS 6 for 7th generation tablets are not released yet, so it's not possible to install it yet. It is not sure whether Amazon will release it ever, or just keep maintaining the Lollipop Fire OS 5 version either. It might be best to just root it, you can install it later if they release it. (There is a way to go back to stock which will re-enable OTA updates. That will not leave any traces of rooting)

Even with root you won't be able to install a clean Android ROM, because the bootloader is locked. (No custom recovery either) But, you'll still be able to remove bloat apps, change launcher, install Google apps, speed it up considerably by adding a swap partition, install Xposed, etc.