I’m currently using readera but it’s not that good (text scaling is behind a paywall)
Edit:the ability to put stuff into categories would be neat btw
SumatraPDF or zathura + zathura-pdf-mupdf
Librera Reader - either from F-droid, or you can use Obtainium to install directly from repo.
Play Store version is paid but comes with additional features including network library integrations
No general reader abilities are behind a paywall though. So fdroid(free) version is recomended
What sort of network library integrations are you referring to? The version I install directly from repo has Project Gutenberg and Internet Archive preconfigured, and I can add my own Calibre and OPDS libraries too.
Edit: the Play Store version (Pro) is also available via the repo, along with the F-droid release. Another reason I avoid F-droid and install direct from repo using Obtainium.