Comment by geogriffin

FWIW, you can write the conditional compilation example like so:

  fn read_keys(#[cfg(feature = "splitapple")]
               port: nrf52840_hal::pac::P1,
               #[cfg(feature = "keytron")]
               port: nrf52833_hal::pac::P0) -> Packet {}

I suppose the compiler could try to suggest that as a fix.