PDF Reading in-app, not download and open local (android/ios)

I really want to use the nextCloud app on Android to read PDFs and have that app do the PDF rendering. Namely so that my progress in PDF files (and other docs, like epub, or whatever) are kept server-side, instead of on my Android device.

Considering the web interface already does PDF rendering instead of downloading and opening local, I think this would be an extension of an already reasonable expectation, that PDF rendering is done in the client (web, and in this case android/ios).

Any chance we can get this to be a thing? Please? :)

I'm sure iOS users would appreciate the same thing too (I don't have any iOS devices).