Apple Watch has the smartwatch market largely to itself, selling millions of units each quarter while its nearest competitors are lucky to sell in the hundreds of thousands. On Wednesday, research firm Canalys estimated that Apple (NASDAQ:AAPL) shipped nearly 7 million Apple Watch units in Q2 and Q3 combined, the first two quarters of availability. Meanwhile, Wall Street analysts estimate that Apple sold 6 million Apple Watches during that period. Canalys didn't break down shipments by quarter, but Wall Street analysts estimate that Apple sold 3.5 million watches in the September quarter. Apple's closest rival shipped fewer than 300,000 units...