I’ve got an old Lenovo Tab3 850M table, running Android 6.0.1
It’s pretty vanilla and I haven’t installed any custom ROMs or rooted the device. The battery is in pretty good condition and the table can idle for around a week I think.
It has an 8 inch IPS display, Quad-Core 1.0GHz ARM Cortex-A53 CPU, ARM Mali-T720 MP2, 500 MHz, 4-Cores GPU, 2GB of RAM, and 16GB internal storage. The cameras are pretty terrible (even for 2016 standards), and the battery is 4300mAh.
What useful things can I do with it?
I’ve been ok with my Galaxy Tab S6 Lite, which is quite a bit newer… But I have to ask, are you reading with black text on a white background?
Yes.
Try the reverse, see if it helps. I use a very light grey on a black screen.