Problem
You don't own your Kindle books. Amazon merely sells you a license to access them. That means they can just decide to pull books that you've bought at any point and you can do nothing about it. To be fair, in practice they generally don't, but they can. Now that they don't even let you make backups, I've decided to move away from the platform.
The only real alternative is Kobo, but their books are DRM protected as well and they don't synchronize highlights and annotations for non-Kobo books.
There are great (mostly Android based) ebook readers and e-ink tablets, all with horrible software. There are great open source projects for library mangement and reading, but nothing that just works.
Vision
You go to this website. You search for a book you want to read. You will be redirected to a DRM-free seller, buy it, and it's available in your naduba library. Already bought it from some other seller? No problem, just upload the epub / pdf.
To read it, you buy the e-ink device you want, install the naduba app, open it, log in, and your whole library is there. You can make highlights, you can attach normal or handwritten sticky notes to those highlights. If you feel like it, you scribble right into the book.
When you finished your book and want to revisit your notes, you simply click on the book on this website. It opens, all highlights, sticky notes, and handwritten comments on pages were automatically synchronized. (With your phone, tablet, and second ebook reader as well, obviously.) Btw, we're living in the 21st century, so your handwritten stuff is searchable.
That's the case for all of your Substacks, saved websites, and RSS feeds too. Those are ingested and kept in a reflowable text-only format so you can read and annotate them on your ebook reader without getting eye cancer.
It's your library and you own it. Having everything in the cloud is comfortable because it enables all of those nice features you just used. You still want a local copy. No problem, you simply click on the export all button and it starts downloading everything, including all highlights and annotations, to your computer.
The Plan
1. An epub web viewer that shows highlights, annotations, and handwritten annotations from BOOX devices (because that's what I bought) on your pc.
2. An Android app that syncs annotations, highlights, and reading progress from the device's reading application one-way to naduba. (BOOX only)
3. Support other devices, support pdf.
4. The Android app becomes a reader and editor, which enables two-way synchronization.
... (we will see about the other stuff when it's time, this is a side project after all)