[esrauch]

> principle, you could perhaps statically link protobuf into the CPython executable, but I really don't think Google is doing that.)

Yes, we actually do exactly this (not just protobuf but generally all of the other C code with it for the given application). But there are other approaches that can work.

> But also now that header is deprecated anyway

It's deprecated exactly because the preferred/supported/default runtime is the upb based runtime. The odd gencode design is what made that transition possible as an implementation detail. So the deprecation is just the same topic here, that people successfully setting up the dynamic linking is not really realistic/viable unfortunately, and the effort for open source support is spent making the best behavior on the upb runtime which can't have that feature.