I'm trying to do the same. All my notes are backed up to a private repository, would be pretty kick-ass to get it synced with my iphone. Let me know if you find it out!
https://help.obsidian.md/Obsidian/iOS+app#Working+Copy
Sorry Android users, you're on your own to figure this out.
edit: I had to figure out how to perform "Setup Folder Sync". This is done within Working Copy. Here's a walkthrough:
https://forum.obsidian.md/t/mobile-setting-up-ios-git-based-...