Third party sync would not work for iOS!
I addition I already tried synology sync for my computers and I run into duplicates often when both computers a running at same time (even when working on just one device actively).
I like the plugin concept but actually it brings a lot of compatibility problems in between them as well as security questions.
I really would prefer to integrate some of the high ranked plugins into the core rather than thinking about outsourcing this kind of basic functionality.
It feels like starting to conflict more and more with the initial approach of having my notes secure under my control “forever”.