I’m looking for the same. I’ve used moon reader on android and it can sync progress between devices. Also it supports WebDAV, so calibre may work but I haven’t tried it

Put any person who has zero computer experience in front of a windows computer or Linux computer and I doubt they would say the windows computer just works and the Linux one doesn’t.

In my experience, usually with Linux they have less problems and it’s easier to use. Until they need an application that only works on Windows.