Can we use a lightning app or detector to decide when to stop and restart?

Yes, as a backup but never as a replacement for your own eyes and ears. Under the NFHS lightning guidelines (October 2024):

• If data from a nationally connected lightning detection network is available, monitor it closely whenever storms are possible and during delays.
• Suspend play when lightning is within a 10-mile radius of the event.
• Don't resume until at least 30 minutes have passed since the last lightning within 10 miles.
• Never rely on a detection device if the sky looks threatening, you hear thunder or you see lightning. What you see and hear always overrides an app or detector.