Markor supports Zim files, as of a few versions ago

I “solve” this problem by storing my phone’s notes in IMAP, and dumping them periodically into my main notes.

That solves writing. I find it actually works because phone notes tend to be write only — little snippets of information that record something important and never get edited again once they are written, to be turned into a “real” note at a later date, once in a system that supports “real editing”.

For reading notes I dump everything onto a personal website.

I second that... There are a lot of times when I want to make notes or find information that I want to add to my Wiki (hosted on my desktop) from my phone or just want to search for something and having an android app that lets me do that would be fantastic.