For opening your app's notification access settings you can use this Kotlin function:

fun openNotificationAccessSettings(context: Context) {
    try {
        var intent: Intent?
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
            intent = Intent(Settings.ACTION_NOTIFICATION_LISTENER_DETAIL_SETTINGS)
                .putExtra(
                    Settings.EXTRA_NOTIFICATION_LISTENER_COMPONENT_NAME,
                    ComponentName(context, NotificationListener::class.java).flattenToString()
                )
        } else {
            intent = Intent(Settings.ACTION_NOTIFICATION_LISTENER_SETTINGS)
        }
        val value = "${context.packageName}/${NotificationListener::class.java}"
        val key = ":settings:fragment_args_key"
        intent.putExtra(key, value)
        intent.putExtra(":settings:show_fragment_args", Bundle().also { it.putString(key, value) })
        context.startActivity(intent)
    } catch (_: Exception) {}
}

Replace NotificationListener with your notification listener service class name.

Make sure the service is added in AndroidManifest.xml, for example:

<service
    android:name=".NotificationListener"
    android:enabled="true"
    android:exported="true"
    android:label="NotificationListener"
    android:permission="android.permission.BIND_NOTIFICATION_LISTENER_SERVICE"
    android:foregroundServiceType="connectedDevice">
    <intent-filter>
        <action android:name="android.service.notification.NotificationListenerService" />
    </intent-filter>
</service>