CONRAD ONYANGO THE Silicon Savannah moniker may be wearing a little thin but second-hand clothing trader Offie Otieno is living proof that East Africa's tech and innovation hotspot is as dynamic as ever, despite the COVID-19 pandemic. Otieno's platform of choice for his hustle? Whatsapp.  Offie Otieno is standing inside his stall on Moi Avenue on a busy weekday morning, hand in pocket. The second-hand clothes trader would usually be busy scanning the central Nairobi crowd for potential customers. Today, he pulls out his mobile phone and, unlocking the screen, clicks on the Whatsapp icon and moves to the app’s status. After scrolling through his…