Comment by NotPractical

Those are vague examples of what the NDK could be used for, not an exhaustive list of all supported use cases. And Syncthing is really just trying to re-use their existing code on Android (example use case #2). It doesn't even require low-level syscalls, it just needs to be able to call fopen() on files which the user has explicitly granted to the app, which you'd expect would be available within the application sandbox.

> And most likely safety, not having C and C++ dealing directly with random bytes from untrusted files

You might as well just axe the entire NDK if you're worried about unsafe code.