For ensurepip we are shipping prebuilt pip & setuptools wheels. These wheels are pure Python, but I'd argue they still fall under the rule to not ship anything prebuilt if we have the source.

To fix this we could simply use the already built setuptools to build pip and setuptools wheel from source and then include them in the package. When bootstraping Python, we build it without ensurepip, build setuptools and then rebuild Python and use the built setuptools to produce the wheels.

Keep in mind, ensurepip is required by some tools and it is a valid use-case to use it in virtual environments, so it shouldn't removed.