It's not a great alternative though. After all, Apple doesn't even provide a version of Safari for non-Apple platforms. They used to, but they stopped with the windows version years ago.
That means Safari will be locked in at most at the Apple marketshare which is only about 8% on desktop: https://gs.statcounter.com/os-market-share/desktop/worldwide... . Not really a monopoly-breaker.
And not everyone on Mac uses Safari of course, I didn't use it much when I still was on Apple because Firefox could sync my bookmarks with all my other computers.
On mobile it's a different story of course (they are at 31% there, and nobody is allowed to run a different engine) but a browser isn't so important there because most services have en app.