I've never seen this before:
On Facebook, owner wondered why his Disco was low. Compressor removed, just pump up at the same time as you check your tyre pressures. See the valve mounted into the panel
IMO it's just a stupid botch, the same efficiency like a massage to a wooden leg that would have been nice as a backup for an existing SLS, once an owner decides to remove/disable the compressor/SLS then he should fit coils and get done with it cos most of them are converting to coils to not buy new air springs which are the most common failure
I've got a pair of those valves plus a bit of pipe in my toolkit purely as a short term emergency fix if the compressor fails. As to fitting them on full time .......