I would say that the C family languages are traditionally native of most operating systems [1] as they are polyglot and can directly speak whatever C ABI dialect is used there; they also work with the native platform tools.

C# is really native of the .Net platform and although it can be AoT compiled it either can't talk directly with Win32 or the interfacing is not seamless. Also it has its own set of tools.

Android and iOS are interesting because although they are clearly unix derivatives, the unix interface is not the primary interface; so arguably C and C++ are not really native there while Java and ObjectiveC/Swift respectively are.

[1] Or to be fair, of unix and any operating system that can be made to look like unix (Windows).