Yup! It's just the mask. A ventilator is a pretty complex, configurable piece of electronics and machinery. It needs to push air in and pull it out at specific

Yup! It's just the mask. A ventilator is a pretty complex, configurable piece of electronics and machinery. It needs to push air in and pull it out at specific volumes and pressures (usually hand-calibrated to the individual patient by a doctor), and do so with a pressure curve that does as little damage to the lungs in the process. The machines are indeed in short supply (which this doesn't fix), but so are a lot of parts that become contaminated after use on a patient (which this does fix). See also that project going around for 3D-printing replacement valves.