Any industry that involves data exchange between devices as a core aspect of its processes can implement wearable technology seamlessly. It can help build a range of apps across fitness, supply chain, finance, warehouse management, healthcare, consumer electronics, etc.
To enlist a few app ideas: Wallet apps for instant payments in smart wristwatches | Calorie and workout tracker in sportswear | GPS based smart shoe apps for trekkers, runners, and delivery men | Smart glasses with embedded AR/VR for workers in warehouse management | Smart badges for preschool kids to monitor their movements | Patient management apps for wearables that help detect falls, heart rate, oxygen levels, etc. | Apps for maintaining social distancing rules