I recently discovered e-readers, these devices are specifically designed for reading, modern ones use an ‘e-ink’ display which is a game changer in comparison to regular led displays because it doesn’t cause as much eye strain + it can be used outside.
I recommend the PocketBook basic lux 3, it’s the cheapest one ($85-100) without a touch screen (trust me its better with buttons). You can use free software like Calibre to upload .epub/.pdf files. Even manga looks great on it.
They will make your reading much much better.
Got a Kindle (broke the old one and these guys gave me a discount code lol), but sideload the ebooks (and jailbroke it)
As long as it has an ‘e-ink’ display it’s good. Some kindles have LCD/LED screen so those are not very useful.