Is the requires-python entry part of the package’s metadata or a consequence of the language used in the package (if so, then shouldn’t it be determined at package build time and not provided by the user)?
Also, considering the goal of having the metadata storable outside of the package so package indexes could index the package metadata, what are your thoughts on the provides entry (Core metadata spec)? After a bit of thinking, maybe this is worth discussing in a future metadata feature version. (My thoughts came up when I was thinking of the multitude of TOML parsers in PyPI, and wondered if they provide the same API, then which package is imported could be up to the user)