I surely understand the need for the US based suppliers. Be sure that Oberlo is aware about such demand and working on it!
My suggestion for a workaround here - even though all suppliers are based in China, they are expanding their warehouses to the US. For instance, the "Apex Trading" supplier offers the USPS shipping option. Using this method, items are delivered within 8-15 days. It available in OS marketplace only.
There are some suppliers on AliExpress.com, who have warehouses in the USA, so they provide fast USPS delivery too.