Does this qualify - scenario #1: US —>Guangdong (6 days) —> Hong Hong (4 days) —> US

There are recent changes in Guangdong. Assuming these are your only stops, scenario 1 should work if you can show your onward ticket to Hong Kong when you check-in in US. Scenario 2 works only if you return to China by air. Only Guangzhou (CAN), Shantou (SWA) or Shenzhen (SZX) airports are valid ports of entry.