Utility for reporting current timezone the android device has set. It always emits at least once with default setting and then for each TZ change.

TimeZoneMonitor.kt

interface TimeZoneMonitor {
    val currentTimeZone: Flow<TimeZone>
}

@Singleton
class TimeZoneBroadcastMonitor @Inject constructor(
    @ApplicationContext private val context: Context,
    @ApplicationScope appScope: CoroutineScope,
    @Dispatcher(IO) private val ioDispatcher: CoroutineDispatcher,
) : TimeZoneMonitor {

    override val currentTimeZone: SharedFlow<TimeZone> = callbackFlow {
        trySend(TimeZone.currentSystemDefault())

        val receiver = object : BroadcastReceiver() {
            override fun onReceive(context: Context, intent: Intent) {
                if (intent.action != Intent.ACTION_TIMEZONE_CHANGED) return

                val zoneIdFromIntent = if (VERSION.SDK_INT < VERSION_CODES.R) {
                    null
                } else {
                    intent.getStringExtra(Intent.EXTRA_TIMEZONE)?.let { timeZoneId ->
                        val zoneId = ZoneId.of(timeZoneId, ZoneId.SHORT_IDS)
                        zoneId.toKotlinTimeZone()
                    }
                }

                trySend(zoneIdFromIntent ?: TimeZone.currentSystemDefault())
            }
        }

        context.registerReceiver(receiver, IntentFilter(Intent.ACTION_TIMEZONE_CHANGED))

        trySend(TimeZone.currentSystemDefault())

        awaitClose {
            context.unregisterReceiver(receiver)
        }
    }
        .distinctUntilChanged()
        .conflate()
        .flowOn(ioDispatcher)
        .shareIn(appScope, SharingStarted.WhileSubscribed(5_000), 1)
}