(I know, Amazon!)
Amazon Fire tablets are fully functional tablets running Amazon’s variant of Android. They have full HD resolution, so same number of pixels as your old HD TV, but less than Samsung or Apple. The user interface has an Amazon slant, with their own web browser and the Amazon app suite (Shop, Prime Video, Amazon Music, Audible, and of course Kindle).
They are sold at one price if you’re will to accept Amazon advertising on your screen saver, and at a slightly higher price if you want it ad-free.
I use an old 8” Fire tablet for bathtub reading, including FR. If I should ever drop it in the water it won’t be a big deal.