Apple is set to give its workers an option to reportedly have coronavirus tests once they return to its Silicon Valley headquarters. The company provided nasal-swab tests to the workers returning to the Apple Park office in Cupertino last month.
Since someone could be asymptomatic (no fever <> no COVID), they could also quickly test blood oxygen saturation for silent "happy" hypoxia.
It appears that even upcoming Apple Watch model sensors simply not accurate to properly measure O2 sat: https://www.wired.co.uk/article/blood-oxygen-spo2-covid-wearables