Technically it doesn't "hold" any air as there is no tank.
However the air compressor is capable of producing up to 200psi.
With the 1/8" lines, however, it would take a very very long time to inflate a flat tire or even a low tire, plus you would need to hook a switch to the compressor relay to turn it on and also have a way to divert the air from the shocks to the hose you would be using so as not to over inflate your shocks in the process.
The ESCM is programmed to not run longer than 255 seconds (4 minutes 15 secs) to keep from overheating the pump, although with a manual switch it wouldn't shut off, but it would be bad for the compressor.
With all of that being said, the auto leveling compressor for the Trail Blazer SS/Envoy uses 5/32" lines and it has a switch for turning it on manually and a hose for inflating things. The switch and hose was mounted in a cubby hole in the rear of those rigs.