There is basic support because of another open source org mode app - Orgro (https://orgro.org), - the author was even gracious enough to relicense his code away from GPL, so that I could use it. since GitJournal is shipped on the iOS store and GPL would not be compatible.
However, GitJournal internally expects everything to be markdown + yaml. So anything else are hacks I've done on top. At some point, I want to refactor and remove this hard dependency on Markdown.
Edit: I mistakenly thought the app was Orgzy. I've updated the comment. Sorry.
The relevant libraries are https://github.com/amake/org_flutter and https://github.com/amake/org_parser.
I mean I respect your decision to make it open-source or not, but why does the store matter ?
[0] https://opensource.stackexchange.com/questions/9500/is-apple...
[1] https://news.ycombinator.com/item?id=12827624
[2] https://github.com/KDE/kdeconnect-ios/blob/master/License.md
disclosure: I’m the author of Plain Org.