I use Book Reader (it’s on F-Droid) for my phone, which works well enough… don’t know how it performs on a tablet or if it has the features you’re looking for.

I would wholeheartedly recommend a dedicated e-reader with E-Ink display for more ‘serious’ reading (I have a Tolino for the evenings/bed. Depending on where you are located you could also look into PocketBooks or Kobos… just make sure they’re not chaining you to a closed ecosystem like Kindles).