The app for Syncthing on iOS is called Möbius Sync. You can find it in the App Store: Möbius Sync on the App Store
I’m not very familiar with GitHub sync, and personally, I only sync manually for one collaborative graph that I use on one machine. Have a look at the article I linked to, or search the forum for “Github sync” as there seem to be a few discussions about it already: Search results for 'github sync' - Logseq