My advice is to forget the website building aspect and turn it into plugins for Wordpress and the popular website builders. A website builder is not a good pick for a side project if your intent is to generate passive income. You have to be on call 24/7 to deal with server issues (and they will happen). Starting with plugins is great for side projects because they are easier to maintain and it will allow you to gauge if there is really a demand for keeping a website in sync with Facebook.