Any USB or Bluetooth keyboard works. macOS maps the Windows key to ⌘ and Alt to ⌥, which puts ⌘ one key further from the space bar than on a Mac keyboard. System Settings → Keyboard → Keyboard Shortcuts → Modifier Keys can exchange Option and Command for one keyboard, but with Contralto leave them as they are: its Alt+Tab, Alt+F4, Ctrl+Alt snapping and Win+Shift+S read Alt as ⌥ and Win as ⌘, and Ctrl already does what Ctrl did on Windows. If you exchanged them, set them back.
The extra keys:
- Home, End, PgUp, PgDn work, with the Mac meaning: Home and End scroll the document rather than moving the cursor to the line ends.
- Delete deletes forward, as on Windows. Backspace is Backspace.
- PrtSc, Scroll Lock and Pause do nothing by default; a keyboard tool can give them a job.
- Insert does nothing. Overtype mode does not exist on the Mac.
- The function keys act as F1 to F12 unless the keyboard has its own media layer.
Keyboards with a Mac layout printed on the keys exist, but with Contralto a plain PC keyboard's Ctrl, Alt and Win keys do their Windows jobs as labelled.