Open source e reader

I recently got a Sony prs 600 e reader from 2009. The battery is at the end of its life (It lasts about 3 days with heavy reading, and a couple weeks without reading). No backlight, no Wi-Fi, just an SD card that I can load epub files and small PDFs. The screen is slow and the contrast isn't the best. The "touch screen" is the old resistive type where you really need to press with your nail or a stylus. Despite all those flaws, it's fantastic. It's just good enough for reading books.

I read with large text so I don't even need to put on glasses, and it's easier to read than an actual book. Combined with Anna's archive, I'm reading more than I ever have before. No Wi-Fi nd slow screen make the experience feel closer to an actual book than a smartphone. It's great to just have a device do one thing without distractions popping up every minute.

It's all old technology, but it's so rare to see anyone with an e-reader. Probably because they're still expensive and designed to microtransact the fuck out of you.

So do you think there could be a simple open source e reader? I see pine64 is making the "pinenote", but it's still just the developer version, it's expensive, doesn't have an sd card, and looks like it's trying to be a lot more than an reader. Maybe it'll come down in cost, or they'll release a simpler version? The biggest obstacle for making an e-reader seems to be the screen, so maybe the pinenote's screen could become something of a standard.

Or maybe I'm overthinking it, because there's already so many old Kindles and nooks out there that could be improved with a new battery and maybe new firmware too.

Thoughts?