Sadly, they mimic the macOS UI very poorly, and it remains not-possible in Linux to universally remap keyboard shortcuts to match macOS built-in sanity.
Yeah, I really wish I could map Alt+Down to open files in Nautilus so that I can then use the Enter key to rename them like any sane person
Also use waterfox instead of firefox if you want the browser to give you a proper global menu, or use chrome.
I can get a "looks like OSX" theme for KDE easily, but KDE will still be weirdly unstable, and have tons of impedance mismatch between it's components. You can't make a Ferrari out of a Ford by painting it the right shade of red.
I also don't understand how people say Macs are stable. I get the spinny thing that locks up the entire system about once a week.