Health wearables are booming, with both Oura and Whoop eyeing IPOs, but investors remain cautious after Fitbit's struggles and low consumer hardware margins (David Wainer/Wall Street Journal)

David Wainer / Wall Street Journal : Health wearables are booming, with both Oura and Whoop eyeing IPOs, but investors remain cautious after Fitbit's struggles and low consumer hardware margins — Oura and Whoop are eyeing IPOs at heady valuations — From sleep scores to heart rate, our biology now arrives packaged as a dashboard.