HarryMann;
The 320/340 Series aircraft do not annunciate "ground/air" condition directly. I am unaware of the 777's annunciations but I suspect neither does that aircraft.
On the Airbus 320/340 series, two LGCIU's (Landing Gear Control Interface Units) alternate operation each leg and do the air/ground sensing and "decision-making". They have inputs from many aircraft systems and sensors.
Thus, there would be indirect indications (ECAM and others) of an "air/ground" issue - for example, Avionics cooling, which is different in the air. The "ground shift" system on the Airbus takes inputs from all three oleos, the downlocks, the gear doors, flaps, as well as the cargo door positions, selector valves and locking mechanisms and cabin door sills (proximity). You can see that it is not a simple nosewheel oleo extension left-and-right switch.
As described above, the Airbus ECAM screen would annunciate several systems which were not in the proper configuration for ground. There would be ample indication that something was not in order.
Wheel speed is available for anti-skid systems but is not used for air-ground sensing. I suspect along with other sensors, wheel-truck tilt on the B777 is used for air/ground sensing.