C++ has lots to do with Android and iOS.

On Android side, Vulkan, ML, real time audio are all only available via the NDK.

Project Treble allows for Java and C++ drivers, but the large majority of them are actually written in C++.

Real time audio framework, Oboe, is written in C++.

The Play Games infrastructure is written in C++.

On the iOS side, Metal shaders, former driver framework and the new one use C++.

Objective-C++ is part of the SDK and allows for easy interoperability between Objective-C and C++.

Swift and clang build on top of C++, thanks to LLVM.

Finally, C++ is part of the official language list on both platforms.

So contrary to urban myths, C++ has plenty to do with both platforms.