One good thing the EU mandated recently is that you can uninstall Edge. On my gaming PC, I installed LibreWolf from the Microsoft store instead.
That's great. They could do the same with Safari.
They should. But if they can is not that certain.
IANAL, but when I asked a person somewhat involved in EU anti-trust processes, osx and macos aren't even close to be classified as monopolies in most of the EU, so the idea that Apple is abusing their monopoly to enforce their own tech on users, doesn't apply that clearly.
EU antitrust doesn't require a monopoly (or even majority marketshare), just abuse of a dominant position. I still wouldn't bet on them going after macOS Safari any time soon, it's a much weaker argument they've been able to force much because of it (unlike iOS Safari).
They did, on iPhone and iPad.
The way I understand it, the EU doesn't care about Mac at all since it has so low market share.