If I'm not mistaken, "no one has figured out" is factually incorrect. https://ameliorated.info/ blocks nearly all OS network requests (and hopefully all OS telemetry) by physically removing the relevant files from the system (though this breaks UWP apps, .appx, and such), and disables Windows Update to prevent telemetry components from being reinstalled. I use it on a near-daily basis, and it works quite well in most cases, although having a separate admin account by default, not being able to create new accounts (they show black screens), and missing features (Action Center and notifications) do sting, and I'm worried about the lack of security updates. If you do choose to use it, https://git.ameliorated.info/Joe/amecs is important for configuring the system.