I have a Clara 2E. It was some time ago, so I cannot remember all the fine details, but I couldn’t get mine to start without some internet connection. I gave a throwaway email and allowed it to update before I switched off WiFi and could freely move books with Calibre.
To it’s credit, in 3 years since purchase it has not asked for internet since switching it on the first time.
I use this primarily, it’s more than enough for basic tracking and UI is good. A little unpolished at times, but I am yet to find anything on F-Droid which is better.