I have started to use the reMarkable e-paper tablet on regular basis. I
use it to read documents, atricles and books in PDF and to prepare
article review because I can easily highlight errors and make notes to
the documents.
To transfer files in and out I use an USB connection and reMarkable's
built-in WWW server. No cloud is involved here. It requires a modern
Linux (or maybe Windows) machine but there is no need to be on-line.