The full implementation of Travaartje is available as open source software.
Travaartje is the main app, that is build using SwiftUI and Combine. It comes with a full set of unit- and ui-tests.
https://github.com/katoemba/Travaartje/
HealthKitCombine is a small framework that makes a number of HealthKit related functions available as Combine publishers.
https://github.com/katoemba/HealthKitCombine/
StravaCombine is a small framework that makes Strava authentication and upload functions available as reactive Combine publishers. It includes a full set of unit-tests using the Mocker framework.