I stopped using Nova Launcher when it was aquired by an analytics company, since launchers usually have access to a lot of permissions, and I don't trust a company dealing in analytics to operate in good faith with that access. I have used Lawnchair 2 and recently switched over to Neo Launcher.
I use KOReader both on Linux and Android, and I love it! I used Calibre's own reader for epub files earlier, but have since used a bit of time getting to know KOReader and its features better, and it suits my needs very well.