Thank you all. I had a couple of issues.

1. I removed the explicit Identifiable declaration on the Event to not add confusion

2. I rewrote my main as

   @main
   struct PeriodTrackerApp: App {
       var body: some Scene {
           WindowGroup {
               StartTabView()
                   .modelContainer(for: [
                       Event.self,
                       Stats.self
                   ])
           }
       }
   }
   

3. I had to delete and re-install the app on my phone. I think I had a stale data that was causing issues

I can get the app to run on HW now