Very similar to how the recipe book in the game "Potion Craft" is organized. I essentially want to be able to mark pages and assign an icon, letter, symbol, or whatever to the tab. Clicking the tab brings you to that page. I also want the freedom to arrange these tabs around the perimeter of the book.

I'm not even sure what search terms to use to find a software like this. I'm not looking for anything robust, just a simple reader app with minimal page marking with intuitive visual organization.

Does anything like this exist?

I started studying again this semester, and have to read a lot of stuff because of it.
As we get nearly all our Books as PDF and reading on my notebook or my phone gets tiering quite fast. So I'm thinking about getting myself an e-reader to make things go easier.

So i tried to find some ressources to learn about e-readers, but the internet (or search engines) these days seem to suck.
So maybe my lovely tildes can help.

must haves:
can read PDF
needs to make reading this "shitty" two colums pages my PDF have good and easy

nice to haves:
FOSS
Backlight

can somebody help me out? or do you know about a resource where I can learn about the pro and cons of the different e-readers, I'm starting with close to 0 knowlege as I never thoght I will need one, I generally prefere to read proper books.