> The Windows installer also runs pip and IDLE tests before being published [...]

That's good and reminds me that I forgot to mention that for the macOS installer, besides the already mentioned tests, we also download, install, and smoke test a third-party wheel from PyPI using the bundled pip and we also do a visual inspection of the release's changelog by launching through IDLE the docset bundled with each installer. If the Python binaries included with the installer are built for multiple CPU architectures (macOS universal binaries), we would also attempt to ensure that the test suite is run at least once on each architecture (as of several months ago, we no longer regularly distribute such binaries but there's a good chance we may need to do so again in the not-too-distant future, for example, if Apple introduces macOS machines based on ARM CPUs).