I'm not convinced there is enough real need for this to justify implementing and supporting it.

Using shared memory wouldn't be possible with built-in Python objects; one would have to use a special-purpose library for this, or perhaps use something like ctypes. It seems to me that in any case, once someone is doing those, they might as well use those same tools to also create and manage shared resources such as shared memory.

Therefore, even if we allow creating such shared resources, it doesn't seem to me that they will be very usable without a lot of extra supporting features.

In other words, I'd like to see at least one convincing use-case for this before considering any implementation.