The thing that makes the Mac the Mac is not the window chrome.

I’ve been keeping my eye on that and it will probably come closer than anything else to date, but I’m skeptical that it’ll nail everything so long as it’s using Qt. Much of what makes macOS interesting is rooted in Cocoa, so a good macOS clone is going to have to be built in something that’s a close analogue (if perhaps modernized in some ways) to Cocoa.