Unable to use without proto_api despite `enable_pyproto_api_setting` unset

I wanted to use this in an environment where the pyext for proto_api wasn't build/installed and as enable_pyproto_api_setting is disabled by default I assumed this would work.

However the build failed already due to an unconditional dependency on @com_google_protobuf//:proto_api and include of python/google/protobuf/proto_api.h

I made a couple changes such that it builds with the version TF 2.13.0 uses: https://github.com/Flamefire/pybind11_protobuf/commit/f49bc416cad082d9fb514d4f823f5f597ebffa2e

However on current main it seems to be much harder as now check_unknown_fields depends on that too which makes it look like it may not work that easily anymore.

Is there interest in getting this fixed/done? Any feedback on the feasibility of the above change/commit?

The usecase was to compile TensorFlow with a pre-installed protobuf to avoid conflicts when using potentially different versions in one environment.

Start by inspecting the unconditional @com_google_protobuf//:proto_api dependency and the include of python/google/protobuf/proto_api.h. Then trace how check_unknown_fields depends on proto_api and compare the current main branch with commit f49bc416cad082d9fb514d4f823f5f597ebffa2e. Done means the project builds without the proto_api pyext when enable_pyproto_api_setting is disabled.