This is one of those things that I geek out on as a former macOS user.
> 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.
> 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
[2] https://github.com/psifidotos/applet-window-title
[3] https://github.com/psifidotos/applet-window-appmenu