[Quoth]

I don't care for sync or Cloud. Just loading and deleting via the laptop Calibre GUI.

I don't want to use a file manager or badly designed App menu. I want an App on Android that as far as the App and Calibre is concerned, is like a physical ereader. Connect to USB, make change in Calibre (add or remove book), eject and then simply open the app and find the book is in the "app" homescreen or "Library" under recent.
Apps that only "import" from somewhere else on the phone storage or need the phone's filemanagler are smelling of DRM or incompetence.

I think moon+ you need the pro version to get rid of adverts and it costs money?

Seems bloated.