Sails make okay shade for a few months, before U/V turns them to rough toilet paper. You can not make an effective tent out of the, either. It will be leaky and drafty, not suitable for habitation or testing. A rope barrier is not going to keep people, or animals, in or out of an area! There are people that do this kind of stuff for a living!Masks and other PPE gear can be purchased and shipped from China. We need to build up domestic PPE manufacturing capacity, but probably not today.
Anarchists - and the greater sailing community may be able to help fabricate custom equipment for hospitals. Already, 3D printing has made $10k valves available in minutes for about $1. The sailing community's experience with stainless steel might be extremely relevant.
Old sails might be useful as partitions and tents for outdoor testing or triage facilities. Old lines are likely useful for securing tents or crowd management cordons.
My sailmaker charges extra when people want to repurpose sails! He compares it to recycling toilet paper. Sure you CAN do it, but WHY?