Is it possible and cost-covering to create an ad-sponsored service that discloses what ad networks collect about users - i.e. age, location, preferences, interests, pregnancy, illnesses etc?

Because let’s be honest - all of us know that a lot of data points are being collected about us, countless articles have been written about the insanity of cookie and user-data monetization networks - still it appears to be a privilege to few to tap into that data trove.

I personally haven’t seen an effort to try and make this transparent. Efforts like this page are commendable and informative, much like amiunique or other services - still they lack the tangible information that sharing this information with “the world” reveals about an affected individual.

Why hasn’t this been done yet? Why is this seemingly not trivial?