I'm also not a fan of the -0 option. I'm OK with the ability to list available interpreters, but there's nothing about -0 as an option that says to me that's what it's for.

I'm not a huge fan of including the list in the standard help, as py -h already generates the launcher help followed by the Python help and so is pretty verbose.

Maybe just bite the bullet and use "py --list"? It doesn't clash with any existing Python argument, and the core interpreter doesn't typically use long options, so we're probably reasonably safe grabbing --list.