There is no direct connection between the product and people's engagement in social media.
You can create a public that promises to launch a new product that will solve the user's problems in the future (when it will be ready).
While the product is not yet available, you can write helpful posts that solve some pressing problems of your target audience.
Each such post is easy to boost - for 10-15 dollars, you can get about 100 followers and lots of likes on Facebook (provided that the ads targeting, audience pain, and post content match each other).
When launching the product, you will already have a loyal audience with a high engagement rate.
To succeed in that strategy, one should concentrate on a psychological portrait of the audience long before creating a product.