Enforce the kernel team must be separate from the application layer - let other people build operating system UIs on top of the kernel.

For the operating system team to be separated from the product teams.

Even go further and unbundle the product teams - make office separate from bing which is separate from edge, etc.

Just make sure you also do it to Apple, Google, etc.

This is what the US almost did in the 90s.

EU cannot tell Microsoft in general what to do.

Indeed, the AT&T case at the US is the textbook example, it's worth looking at it.