How to link against the C++ API using the Python package?

I want to link against the C++ API. I know there is the Bazel target //, but this does not get included in the Python package.
I see that in the tensorflow Python package there are the C++ header files in the include directory. If they are there I should be able to link against something. I see there is there, but it is missing symbols like xla::HloComputation::CollectUnreachableRoots. This symbol is present in ./python/ Should I link against it? The leading underscore and internal in the name suggest this is not going to be stable.