The only integrations that matter to me are Messages and notifications for phone calls, neither of which are even available on Windows AFAIK, and could just as usefully be implemented as a Web app as a native Windows app if Apple chose to do so.

Oh, and USB tethering, but in my recent experience that's harder to get working on Windows 11 than on Linux (had to find the correct driver manually on catalog.update.microsoft.com as neither Windows Update nor any of the Apple Windows apps installed it, only to have some update or other remove it without my knowledge or consent a few weeks later).