Many students uses document viewer and scanner daily for storing notes but there aren’t any good privacy friendly or FOSS application for Android out there. Playstore is filled with Chinese application which I don’t trust at all but have to use it anyway.
Is there any application that is good for document viewing ( PDF, Ebooks etc) and good at document scaning which is also FOSS. Both could be separate or bundled together.
The only FOSS ebook reader I know is Librera
For a scanner tho, it is much harder. I have used OpenNoteScanner before, but it hasn’t been updated in 2 years. As I bought a scanner compatible with USB sticks since then, I have not cared about scanner apps. I would not recommend using ONS, but if you don’t care about it being roughly 2 years old (without updates), it might be an option for you.
For ebooks, and .pdfs, look no further than Librera. It’s a great tool, that is cross-compatible with desktop software. It’s not as good as some more popular proprietary stuff… but it’s the best FOSS option, I’ve come across.
Document scanning is hard. I’ve tried OpenNoteScanner, but imo, it’s not fit for purpose. 9/10, the document comes out looking terrible. One of the better options, but even then is not great, is OpenScan. Do note, that it’s NOT on F-Droid. you’ll need the Play/Aurora store to download/install it. It can be a bit finicky, and can take some time to give a decent shot, but It’ll do… If you want to stick to FOSS. Honestly, if you’re not using a custom ROM, take a look at your phones default camera app,. It’s not FOSS, but several brands have in-built document scanning features, that far outshine both these offerings. If that’s not an option, consider buying a physical scanner.
Not sure about the best PDF viewer, but the most secure PDF viewer is probably GrapheneOS’ PDF Viewer (which can be installed on any Android ROM).