Surprised there isn’t something that does an almost perfect OS X emulation
• menu bar: one, at the top of the screen. I think KDE had this, and there might have been a somewhat working extension for GTK that doesn't exist anymore.
• keys: CTRL is mapped to Alt; Alt is mapped to Win. This is a start. ⌘C and ⌘V: work as Copy and Paste in Terminal, ^C and all the other "control" keys work as expected in Terminal. I used to configure Terminal keys using AutoKey. I haven't been able to make ⌘← and ⌘→ work in text boxes - sadly it's hard-coded in X11 to do what Windows does.
• windows: Smarter window positioning and sizing especially with multiple monitors. I miss Zoom: the button that sizes the window to perfectly and minimally fit the content without scroll bars.
• too many additional items to count like ⌥8 to type bullet characters.
> menu bar: one, at the top of the screen. I think KDE had this, and there might have been a somewhat working extension for GTK that doesn't exist anymore.
KDE has this if you use the Window Buttons[1], Window Title[2], and Window AppMenu[3] plugins.
> • keys:
Plasma Desktop lets you remap keys easily, and you can use setxkbmap elsewhere. I haven't tried remapping the ⌘ key for terminal usage, though, but I've remapped most of the macOS shortcuts I used to use.
[1] https://github.com/psifidotos/applet-window-buttons