Name: Zone 2 Keeper - Heart Rate Zone Field
Author: RiversideArt

Free from the makers of Fuel Coach (https://apps.garmin.com/apps/9d780302-5805-428a-89cd-f48a8967946a) and Sweat Loss Estimate (https://apps.garmin.com/apps/b25cb726-1c00-48da-af2e-cdde925c149a), two paid fields for fueling and drinking on long sessions.

Set the bottom and top of your zone 2 in settings. The field counts the time you spend inside the band and tells you whether you are above or below it. If you stay out longer than your delay, it plays one tone and vibration, then waits until you are back in the zone before it cues again.

Add it to a data screen of your activity like any other field; it asks for no permissions.