The parallel API would have to be:

json.dump_bytes
json.dumps_bytes
json.load_bytes
json.loads_bytes

That is hardly an improvement over:

json.bytes.dump
json.bytes.dumps
json.bytes.load
json.bytes.loads

It doesn't need to be documented as a completely separate module, it can
just be a subsection in the json module docs with a reference to the
relevant RFC.

The confusion is inherent in the way the RFC was written, this is just an
expedient way to resolve that: the json module implements the standard, the
bytes submodule implements the RFC.

"Namespaces are a honking great idea; let's do more of those"