I've decided with all my commercial e-readers that the USB+calibre is my only option as I do not wish to share my reading habits with the zillionaire overlord.

There might be new and fancy UI or something, but I spend 99% of the time only flipping pages so the outdated UX is nothing compared to the privacy I get.

Ancient Basic Kindle works still nicely and so does 1st gen Paperwhite + the few Kobo's we have in the family.