Can I set the alert notification to specific products only?

I do not want to apply the notification alert to all products in my store but only to a few ones I specify. Is this possible?

Unfortunately, this is not possible. Since the app is dependent only on the data gathered from your Shopify inventory, it is designed to apply this setting to all products in the entire store and there is no setting in the app that will allow you to specify which products the customers can subscribe to.