Various questions and comments:

0. Steve: For more than one reason, I want this to be and remain an added alternative rather than a replacement of the current installer directly available on python.org.  Can you assure us that the latter are not going away?  I would have the same concern about adding something to the Apple/Mac store.

1. Ned: Since enhancements are not normally backported, it would be nice to have your approval, in whatever form it took, recorded here and not just in private email.  I give a reason below.

2. Installers are always experimental until tested by multiple users on multiple machines.  Even then, installation specific issues can arise.  As I remember, the current installer, when new in 3.5, needed a shakedown period.  One installer-specific issue was the initial working directory.  To have a Windows Store Python ready for 3.8, we need to start now.

There was once an issue where one of the installers failed to include one idlelib file. I believe it was help.html. I since added idle_test/test_help.py, which would now fail with something like "No such file or directory: 'C:\\Programs\\Python37\\Lib\\idlelib\\help.html'".)
Repository testing does not test the actual binaries that users install, in their production context.

Steve, assuming that I can access the Store, should I be able to install both PSF 3.7.2 and Windows Store 3.7.2 simultaneously?  So I could test both IDLEs that beginners might install?

3. Anyone: Though it is not essential that I know, I am curious what 'restricted' versus 'non restricted' mean to Windows Store, and why Python can now go there.  My search only came up with age restrictions, which python does not need (in my opinion).

4. While most PRs should be complete in themselves, reasons such as ease of review may suggest splitting one conceptual Pr into pieces.  They just have to be reviewed together, or with expectation of a needed followup (and a revert if it does not appear).  I have done this to get readable diffs for major refactorings that moved and edited multiple chunks of code in a large file.