Amazon Fire HDX 8.9" Tablet (Includes Special Offers), Full-HD 339ppi Touchscreen, 2.5GHz Quad-Core Processor, Dual-Band Wi-Fi, FireOS - (Your Choice: Storage)
This is a fourth gen 2014 Kindle Fire HDX 8.9. Its the most powerful Amazon tablet ever made. It has a much faster cpu (Snapdragon 805 with Adreno 420), the highest resolution screen (2560 x 1600), Dolby Atmos and very high performance AC wireless networking.
I've bought these "certified refurbished" Amazon devices from Woot before, and they looked and worked like new. Woot is a subsidiary of Amazon. The regular kindles I've bought from them had battery life equaling a new one, so it looks like the batteries are swapped for new ones in the refurbishing process.
This is stuck on an older version of FireOS that I believe is built on android 5 lollipop, they generally are very resistant to unlocking the bootloader and/or installing custom roms. Older versions of the 8.9 could be hacked but these are as likely to brick as they are to take TWRP and something like LineageOS.
HOWEVER, if you like the Amazon ecosystem, like to read on a tablet vs an e-ink display or just want to consume media these are beasts with gorgeous screens and sound. VERY different from the current el cheapo Amazon tablets with slow cpus and low resolution screens.
For what it is and the condition they're likely to be in, this is a very good price. I see these for $150-250+ used with dings and scratches. If you can even find one. Amazon has 3 of them for sale from 3rd party sellers used at $259 and up.
You can install the Play store if it comes with fireos prior to 188.8.131.52. I'm looking into if it can be done with V5.xx. Most if not all apps from the Amazon app store are compatible with it.
I got one as my son uses a 2013 7" HDX (the second most powerful Amazon tablet ever made) to read on in dark rooms and likes using it to watch shows and listen to music. This is bigger, faster and has a better screen.
Amazon product page for reference.