Can anyone tell me why Trump& the Feds are seizing hard-to-stock coronovirus medical supplies? It was in the headline news this afternoon.?

To direct them to the areas in the USA where the need is the greatest.

What good does it to do for Podunk, AR to receive a million masks when thousands are dying in NY every day?

Because the ill prepared Democrat leadership of so many states are unable to order and procure their own supplies and so the Trump administration has had to become the equivalent of a clearing house . 

To give away to the needy

If it was "headline news" than please provide a link. 

They are raiding hoarders and giving them a fair price.