Accessing protobuf /protobuf_version.bzl (for build-time reflection purposes) in rules_proto_grpc (bzlmod) project?

[sschnug]

Probably more a bazel / bzlmod than rules_proto_grpc question but:

How can i load the variables from protobuf_version.bzl which lives in the protobuf root-dir when this protobuf(-toolchain) was selected during rules_proto_grpc setup?
Is there any nice way of doing that? Is it even possible?
I tried use_repo(protoc, "com_google_protobuf") and some other stuff within Module.bazel but it seems i'm not understanding how this works as i'm unable to load the file.

Some background:

Setup might look like:

VERSION_PROTOBUF_TOOLCHAIN_SELECTED = "$$$$$-SELECTION-$$$$$" # TO BE INJECTED BEFORE BAZEL INVOCATION
VERSION_RULES_PROTO_GRPC = "5.0.0"
VERSION_RULES_PYTHON = "0.34.0"
VERSION_PYTHON_TOOLCHAIN = "3.10"

bazel_dep(name = "rules_proto_grpc_cpp", version = VERSION_RULES_PROTO_GRPC)
bazel_dep(name = "toolchains_protoc", version = "0.3.3")
# Prevent version skew by matching protoc version to protobuf version, as C++ is the only lang that
# has no cross-version runtime guarantee:
# https://protobuf.dev/support/cross-version-runtime-guarantee/#cpp
protoc = use_extension("@toolchains_protoc//protoc:extensions.bzl", "protoc")
protoc.toolchain(
    google_protobuf = "com_google_protobuf",
    version = "v" + VERSION_PROTOBUF_TOOLCHAIN_SELECTED,
)

# Python
# ------

bazel_dep(name = "rules_proto_grpc_python", version = VERSION_RULES_PROTO_GRPC)
bazel_dep(name = "rules_python", version = VERSION_RULES_PYTHON)

python = use_extension("@rules_python//python/extensions:python.bzl", "python")
python.toolchain(python_version = VERSION_PYTHON_TOOLCHAIN)

and later i want to do some calculation to decide about the version of some package i'm trying to build:

python_proto_library(
    name = "helloworld_proto_py_lib",
    protos = ["helloworld_proto"],
)

py_wheel_rule(
    name = "helloworld_proto_py_wheel",
    distribution = "api_helloworld",
    version = calc_semver_target_package(PROTOC_VERSION, VERSION_API_MAJOR, VERSION_API_MINOR, VERSION_API_PATCH),
    deps = [
        ":helloworld_proto_py_lib"
    ],
)

Now i somehow try to access the mentioned variable PROTOC_VERSION as some kind of reflection (as the result was influenced by external pre-build variable: $$$$$-SELECTION-$$$$$).

The PROTOC_VERSION is an oversimplified example as i'm eventually trying to infer the information necessary to define version-constraints in packages build respecting Cross-Version Runtime Guarantee -> also need non 1:1 mapped values from PROTOBUF_PYTHON_VERSION.