Let me add a few:
- Handover (shared clipboard between devices, continuing tasks on another device)
- AirPlay (both casting and playback control)
- Apps are just self-contained, launchable directories you can copy around, no separate installation step
- Application-centric (as opposed to window-centric) task management
- Tiny things like <Cmd-tab>, keep holding Cmd, click the app to switch to
- Even tinier things, like hold space to move the selection rectangle in the screenshot tool
- Extremely consistent support for all basic keyboard shortcuts like <Cmd-q>, <Cmd-w>, <Cmd-,>, etc, going back all the way to the classic Mac OS
- AppleScript, Shortcuts, (Automator)
- Color management
It's these things I miss on Linux and (Open)BSD the most, not the GUI theme. I actually think the current design (starting with Big Sur) is a huge step backward for accessibility and usability, fortunately this project doesn't blindly copy it.