For the companies without existing domestic manufacturing contacts, the China Council for Promotion of International Trade (CCPIT/贸促会）is working as a platform between some foreign companies and authorized Chinese sellers of PPE. We understand they have a list of suppliers approved by the Chinese government for export.

As Thomas notes below, a number of international firms are conducting due diligence on supplies before the final purchase is made. Control Risks we know for sure, I suspect there are many many others.