If your tablet has been updated to later versions of Fire OS (like Fire OS 7.3.2.x or higher), Amazon patched the simple software entry points. Unlocking these updated devices usually requires a (often utilizing modified scripts via Linux).
The MediaTek MT8168 chip in this model is more resistant to the "shorting" methods used on older 2018 models. Summary of Models Generation Release Year Custom ROM Status 8th Gen (Karnak) Fully Supported (LineageOS 17.1/18.1) 10th Gen (Onyx) Not Supported (No Bootloader Unlock) 12th Gen Not Supported How To Install Lineage OS On Amazon Fire HD 8 Tablet amazon fire hd 8 10th generation custom rom