Not really for OP, but I've found a couple of really great iOS apps that work well with Emacs org-mode, Beorg[1] and FlatHabits[2]. They're actually both good apps in their own right, that use org-mode files as a backend for their features.
I was looking into org-mode a few years ago but ditched it because the only iOS app I could find at that time couldn't really sync with other devices without a lot of effort, and automatic, reliable synchronization is a deal breaker for me. beorg OTOH seems to be designed with syncing in mind.
[1]: https://beorgapp.com/ [2]: https://flathabits.com/