When I was using calibre-web, I regularly synced the calibre library with rsync to the calibre-web server (a Raspberry Pi). Calibre-web then reconnected to the database overnight so that the changes were visible (can also be done manually, of course). So I only had to call the sync script when needed.

There have been no major innovations since 2015, when eInk Carta displays were already available. In the meantime, there are eInk Carta 1200 displays, which offer a bit more contrast depending on the manufacturer. Kobo Libra 2 is a good example. Since Kobo is not officially represented in my country, I mainly use PocketBook devices. Here, I like the open system and that metadata like genre or series are fully evaluated and displayed. The latest model, Inkpad 4, is not quite cheap, but I can highly recommend it. It has a 7.8-inch display, a long battery life, and USB-C.