With a caveat, Metal is written in a mix of Objective-C and C++, with Swift bindings.

Thus you can do anything Metal with Objective-C and zero Swift.

Also, writing drivers, even in userspace is still mostly C++.

Going on a tangent, even if Swift isn't everywhere still, I would like that Microsoft would be half as serious as Apple, regarding .NET use on Windows, however they aren't even serious with C++.