Alhamdulillah am benefiting your app, Masha allah very convenient & May Allah reward you as Sadaqathul Jaariya - ameen.
My suggestion is that, am Indian & currently in dubai, in both regions they follow same procedures that after Adhan every mosque keep 15 / 10 minutes additional time for jamath prayer except for magrib.
kindly develop in your app for additional options for Alerting jamath salaha after adhan time. So people cannot miss jamath prayer.
Awaiting your positive response
Mob: +971 557493937
Suggestion for alerts jamath prayer