Amazon has been releasing new versions of their tablets every 2-3 years. The Latest HD8 that is out is 2020. The latest HD10 is 2021. They're releasing a new HD8 this summer (2022). None of the previous releases have been upgraded to newer versions of FireOS to my knowledge. They have only been updated to include new "features" and (hopefully) security updates. The new HD8 out this summer will be the only one so far with FireOS 8 (Android 11). I doubt they will update any current Fire tablets to the new FireOS 8. I could be wrong, but based on what they've done so far I think that's correct.