I don't these stockpiles exist. At least the order by the German government seems only to be fulfilled by new production [2] and other governments might have to queue due to few manufacturers [3]. I don't know if in market forces and IP worked to our good here. I think current design challenges could at least channel random good ideas wrt ventilator designs. [1]

1.Montreal offers $200k prize for cheap and easy to build ventilator design - https://news.ycombinator.com/item?id=22637540

2. https://app.handelsblatt.com/unternehmen/industrie/medizinte...

3.https://www.srf.ch/news/schweiz/knappheit-wegen-coronavirus-...