So not a solution you’re asking for but the remarkable e-ink tablet has a great set of apps for mobile devices and computers. It hosts your books in the cloud so you’ll always have access to stuff anywhere with internet. Automatically syncs across devices. Pretty slick.

Yep. Just install Linux, plug it into your router, set a static ip, and install the nas software ya want.

There are plenty of approaches. ChatGPT is great at debugging issues and helping ya through the setup. I did this with a raspberry pi and external usb drive the other week.