I don't think there's even a technical way to do this anymore. Digital ads are not actually audiences anymore (bundles of people labeled a certain way).

IMO the regulation needs to be at the data collection side: advertisers should only be able to collect data on a defined set of dimensions and each dimension should have a defined maximum specificity. Then beyond those, advertising platforms need to compete on making their actual products more compelling rather than making them better at sucking up data.