If you have mixed feelings about Calibre (e.g., powerful, but the GUI looks unpleasant to you), you can use Calibre to help you convert books to EPUB format, then put them in something like a `~/doc/` directory on your laptop, with descriptive filenames.

Then you can read on your laptop, such as with `foliate`, and also sync to an ereader that lets you mount it as USB storage, with a script for which the key part is:

    cd ~/doc && rsync -crltv . "${DeviceMountPoint}/."