Good questions and answers
Can I use my Apple Watch for measuring heart rate?
No. Unfortunately, the sample rate of the Apple Watch is not high enough to ensure a sufficient data quality for this purpose. However, any BlueTooth heart rate monitor which communicates with Apple's HealthKit will do an excellent job!
Will LAPP become available for Android?
Possibly, but it will take a while. We learned that the quality of the sensors differs greatly among Android smartphones. Many smartphones simply cannot generate data of good enough quality for LAPP to accurately derive the trainings details.