FWIW, we could use https://upload.pypi.org/experimental-pep-694/ or a similar unwieldy and unambiguously “not forever” name before this PEP becomes provisional (restricting it to a hard-coded list of packages even) if we need to test out the design with a live thing on PyPI.
If we do that tho, ideally we’ll also have a clear plan to move to https://upload.pypi.org/[maybe, something path under that] directly once the PEP is provisional.