Windows S is completely backwards. If the Windows Store was actually any good, they should make a version without store apps (win32 only) and let customers pay a premium to use signed, vetted, store apps. (Only half kidding...) But this way around, store apps will always be viewed as the cheaper, less featured option.
No one uses the Apple app stop on MacOS because apparently it's terrible. I don't see going to a closed/walled garden system as being any type of meaningful advantage. You're trading off some security/sandboxing for reduced flexibility. If Microsoft wanted something competitive, they'd allow people to add other repositories to their stores, so manufactures could publish their own certs and people could chose to trust…
AFAIK, most major apps are on the macOS app store.