Hi there,
I am an experienced developer with more than three years of experience in web automation tool development. Based on your need, here is a cost effective way to develop a solution:
1. Using a Google Cloud function that hosts the code which runs headless Chrome and checks the blog for new posts (since already in newest -> oldest order, matching the title can give you a clue when a new post has been added)
2. Using Google Cloud Watch to run this function say every ten/fifteen minutes and get the newest posts
For notification, you will need the following:
1. Gmail account for Google SMTP with 2 factor authentication enabled and app password setup (daily limit 500; or use Sendgrid annonymous mail)
2. For WhatsApp notification, you will need a Twilio account, buy a virtual number and enable WhatsApp for Business for that number; this is the most reliable way I know of
I can deliver the entire bot for you to test within 4-5 hours. Let me know what you think of my proposal. Thanks for your time and consideration.