Is HRV (Heart Rate Variability) Biofeedback recommended for Children?

The Stone biofeedback and Flow HRV device are designed for adults. However, given that:
1. HRV biofeedback is completely non-intrusive and shows you how your thoughts control your body, often to improve a health condition or physical performance.
2. The Stone and Flow HRV biofeedback games are free from violence, explicit language, and erotic content.
3. We have testimonials from clients successfully using HRV biofeedbacks with children.

I assume children can use (with adult supervision) the Stone devices on computer or Flow on smartphone and take advantage of benefits the HRV biofeedback technology offers.