The only thing that is stopping me from switching to an iPhone is file level access and Syncthing - is that a solved issue? Anyone care to share?

Yes, for ~7 years now the Files app has existed. Sandboxing is still a thing.

Möbius Sync and Synctrain are the options for Syncthing. Both work, neither are official (nor is the currently-maintained Syncthing fork for Android).