I wouldn't necessarily target a watch as a back-up, rather a complimentary layer. I was thinking of Timers (Switch Tanks, Fuel, etc) or Alerts, that could "vibrate" to get your attention. Maybe even a active list of nearby APT and Freqs. At most you could have a CDI on screen, but That would be pushing it.
Many pilots do not have their Tablet or GPS connected to an audio panel, so the gentle "thump" on the wrist could be a good reminder.