I asked PyPy devs about PEP 756: a memory copy will be needed anyway, because Python str objects can be moved in memory (it’s not possible to pin a str object in memory, or at least, it’s not recommended for best performance). Also, obviously, PyPy doesn’t use UCS-1, UCS-2 or UCS-4 internally and so requesting this format would either fail or have to copy memory. PyPy uses UTF-8 internally.
IMO it’s ok that PyPy has to copy memory. It’s still better than the current PyUnicode_AsUTF8() API which has an undefined lifetime.