Correct. It does, however, write to the lookaside space, which Windows will map back if you access it.

So reading HKLM\Software\Python\PythonCore\3.9 will return all the values that would be there. It's only enumeration that doesn't work. I've reported that to the team responsible, and they think it's not necessary, so I have no qualms about saying that you should *also* look in "SOFTWARE\\Microsoft\\AppModel\\Lookaside\\user\\Software\\Python\\PythonCore". (And if another redistributor also does a UWP package of Python, they'll have their own registry section for it to go into.)

Not writing into shared registry locations is one of the *best* features of this form of packaging, so I'm not inclined to try too hard to break it. Overall the robustness and stability is worthwhile, so it'll just fall to tool developers to catch up a bit, or alternatively win over the team that could just fix it properly.